Introduction to Euclidean geometry
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Lines, line segments, and rays
Difference between lines, line segments, and rays
Discussion and questions for this video
 What I want to do in this video is think about the difference between a line segment (a line segment)
 a line (a line), and a ray (and a ray). And this is kind of the pure geometrical versions of these, of
 these, things. And so a line segment is actually probably what most of us associate with a line in our
 everyday lives. So a line segment is something just like that (for a lack of a better word) a straight
 line, but why we call it a segment is that it actually has a starting and a stopping point. So most of
 the lines we experience in our everyday reality are actually line segments when we think of it from a
 pure geometrical point of view. And i know i drew a little bit of a curve here, but this is supposed
 to be completely straight. But this is a line segment. The segment, the segment is based on the fact
 that it has an ending point and a starting point, or a starting point and an ending point. A line if
 you're thinking about it in the pure geometric sense of a line, is, essentially, it does not stop. It
 doesn't have a starting point and an ending point. It keeps going on forever in both directions so a
 line would look like this (a line, would look like this) and to show that it keeps on going on forever in
 that direction right over there we draw this arrow, and to keep showing that it goes on forever in kind
 of the down left direction, we draw this arrow right over here. So obviously, yyou no I've never encountered
 something that just keeps on going straight forever (forever), but in math (thats the neat thing about math) we
 can think about these abstract notions and so the mathematical purest geometric sense of a line is the
 straight thing that goes on forever. Now a ray is something in between. A ray has a well defined starting
 point (so that's its starting point), but then it just keeps on going on forever. So then, so the ray
 might start over here, but then it just keeps on going (then it just keeps on going). So that right over
 there is a ray. Now that out of the way, let's actually try to do the Khan Academy module on recognizing
 the difference between line segments, lines and rays. And i think you'll find it pretty straight forward
 based on, on our little classification right over here. So let me get the module, let me get the module
 going. (let me, where did i put it? where did i put it? there you go!) Alright, so what is this thing
 right over here? Well it has two arrows on both ends, so it's implying that it goes on forever. So this
 is going to be a line. (lets check our answer.) Yeah! Its a line. (now it's taking some time, oh correct,
 next question) Alright now what about this thing? Wait once again arrows on both sides means that this
 thing is going to go on forever in both directions, so once again it is a line. Fair enough, lets do
 another one. Here, we have one arrow, so it goes on forever in this direction, but it has a well defined
 starting point. So it starts there and then goes on forever. And if you remember that's what a ray is.
 One staring point but goes on forever. So it goes, or more when you think about it, it goes on forever
 in only one direction. So that is a ray. So lets do another question. This right over here, you have
 a starting point and an ending point. Or u can call this the start point and the ending point but it
 doesn't go on forever in either direction. so this right over here, is a line segment. (there you go)
 So hopefully that, that gives you enough ttto work your way through this module. And you might notice that
 when i did this (when i did this) module right here, there is no video and that's exactly what this video
Be specific, and indicate a time in the video:
At 5:31, how is the moon large enough to block the sun? Isn't the sun way larger?

Have something that's not a question about this content? 
This discussion area is not meant for answering homework questions.
would an infinite line and an infinite ray be equally long? That's my question.
Yes. It's a tricky concept because it feels like an infinitely long ray is only half as long as an infinitely long line. But technically, half of infinity is still infinity.
no, look at set theory as an example. if there is a set that extends infinitely to all the positive numbers, and then there is a set that extends infinitely in both directions, with negative numbers and positive numbers, they are not equal set, because even though both are infinite, you cannot match up each element os the positive set with each element of the negative set. In other words, for every centimeter of the ray, there would be twice as many centimeter of line, therefore the line is longer
The definition of something that is infinite, is that it never ends. As someone else said, half of something that is infinite is still infinite. Think of it this way: If you have something that never ends,no matter how many times you divide it, it will still go on forever. You cannot simply put it into "real life" examples relating to us here on Earth.
@Stuart Wickard, you cannot compare infinity=infinity/2 TO 1=1/2, because as one is an actual or definite number, infinity is more of a concept or an estimate, and nobody knows what a half of it is. that's why infinity divided by two is still an infinite number(infinity)
Quite an interesting discussion here. Are we are even measuring it in reality at all, or as solely a mathematical concept? In the real physical world, I would think it depends on if space itself is curved or flat. I don't think curved space could be infinite. But I'm not an astrophysicist, just offering my two cents.
不相同，直线与射线是2个概念的，射线有起始点
A line is an entirely different concept as a ray. It cannot be answered fully no matter what you do, but if necessary, you should think about the following. The answer depends on whether you are using Euclidian or nonEuclidian geometry. It further depends on whether you are using practical or theoretical science. In Euclidian geometry, the ray would not meet its starting point from the other side like you would if you went around the world. Therefor, in practical science the line would be longer than the ray. However, since infinite means going on forever, the ray would go on forever and so would the line, they would be the same length in theoretical science! In nonEuclidian geometry, the ray would basically wrap around the universe like you might wrap around the world. Therefor, in that case it would meet itself from the other side, and so pass through the same points as the line would, so in practical science they would be the same length. But in theoretical science, the line would cover twice the universe's length by the time the ray would cover the universe's length once, so in theoretical science, the line would be longer. If you see this question on a math test, writing down that both are true or neither are true or even that it is impossible to answer would be good, but you should explain why too. Does this help?
They would, because only one side of a ray goes on to infinity, double infinity (which is what happens with a line) is still the same as normal infinity. So yes, a ray and a line going on forever would be the same length as each other.
The ray is equally long on one way and on the other way it stops or ends so it shorter. Over all though they both go to infinity so the are equal if u count both ways.
it is a tricky concept.it feels like an infinitely long ray is only half as long as an infinitely long line. But technically, half of infinity is still infinity.
Yes, Because if you think hard about it you will find out that they both keep on going forever and will never stop so they will always be the same
Yes. There's no biggest infinity.
A line or a halfray going to infiny, they are all going to infiny.
"some infinitys are bigger than others." = wrong!
You can compare infinity tending towards  or tending towards +, but you can't compare 2 infinities, they are considered as equal. There is halfray, but no halfinfinity!
A line or a halfray going to infiny, they are all going to infiny.
"some infinitys are bigger than others." = wrong!
You can compare infinity tending towards  or tending towards +, but you can't compare 2 infinities, they are considered as equal. There is halfray, but no halfinfinity!
just watch the video from 0:00 3:38 and learn stuff from it :3
Another way to think about it would be, if you cut an infinity sign in half, you get a circle, which is still infinite but in a different way.
no and yes. no because a ray extends in only one direction while the other point is stationary.but a line extends endlessly in both directions .so a ray it will be 1/2 of a line.
yes is because both of them are infinite and no body can measure it.so we cannot say its exact distance.
yes is because both of them are infinite and no body can measure it.so we cannot say its exact distance.
There are different sets of infinity, so no. A ray is not as long as a line.
well I guess it would be just as long on one side and not on the other
A line is 2 rays put together so whatever the length the ray is the line will be two times that.
Yes and no, because "equal" has little or no meaning when you're talking about infinity.
I believe so, since only line SEGMENTS stop at any piont of time.
i agree with the people who said that the ray only goes in one direction while the line goes in two opposite directions
I say no, because a *ray* is going forever but in _one direction_ but for *line* it will go in _two ways forever_. So if you stop both at a certain point the ray will be two times shorter than the line because the line was going in two directions at once and the ray was going in one direction at once, so I would say no, the *ray* will not be as long as the *line*.
P.S.The ones in *bold* are the one we are talking about.
P.S.S. So I say no, if it were yes than...
More
Example:
```
Line Segment
..
Ray
>
Line
<>
```
That is my example.
So that us why I think *Lines* are longer than *Ray*, and this is the main reason, "_The *Lines* go in two different way(s) at the same time, but *Rays* go in one way(s)_".
P.S.S.S. Tell me if _you_ do not get it.
P.S.The ones in *bold* are the one we are talking about.
P.S.S. So I say no, if it were yes than...
More
Example:
```
Line Segment
..
Ray
>
Line
<>
```
That is my example.
So that us why I think *Lines* are longer than *Ray*, and this is the main reason, "_The *Lines* go in two different way(s) at the same time, but *Rays* go in one way(s)_".
P.S.S.S. Tell me if _you_ do not get it.
Like nickspoon said, it doesn't matter if it is a ray or a line because infinity is the concept of things that never end. so basically, they would be the same never ending length.
no because a line is infinite in both directions but a ray is infinite in one direction
Infinity and infinity = infinity no matter what.... so what Gabe said is right they cannot be diffrent lenghts even tho one starts and one is twice the size... (This part refers to a movie skip if you haven't seen it Unless you wanna under stand it better>) Think of it as in transformers... That big cube... it was still the same power even when it was bigger or smaller, that is the same thing with infinity... (END OF MOVIE REFERENCE) As in the example Its the smaller or bigger thing such as ray and line that is equal. Even tho they are diffrent numbers that don't come out right... In infinity multiplicationadditionsubtractiondevision with any number would still come out to infinity so infinity would never ever not be equal to itself.
No. Since a line goes on forever in both directions a ray only goes in one direction. It cannot be parallel.
there are different kinds of infinity. Read about the mathematician Cantor, and the concept of Aleph.
Well no because a ray spreads out infinitely in only one direction when a line spreads out in both directions therefore if you were to stop them from expanding the line would be about twice as long as the ray.
Yes the infinite line and ray would be the same because of how no matter what the lines go on for ever that is why on the end you make an arrow to show that it goes on forever. Also because that the degrees stay the same the small area at the bottom were the two lines meet do not change only the lines length. Now if you connect the lines and one is 20 cm long and another ray line is 5 cm long and you connect the lines the area will be different for both.
but a ray has to end
a line can be as long as you want
a line can be as long as you want
they are both infinite, so yes but infinity has no length so they couldn't be measured. even if a ray has only 1 side going to infinity, half of infinity is still infinity (or a quarter, or a eighth or even infinity for that matter)
Think of infinity as a way to express an evergrowing number. Even if you take half of that number away, it is still evergrowing. Therefore, a ray and a line are the same length.
I think that both the ray and the line are the same length. If you think about it, there doesn't necessarily need to be negative and positive numbers denoting every single point on the line and ray. That case would only be on a plane. If you have any more questions, please reply below. Hope this helps!
In my view (thinking of this as a philosophical question, rather than a mathematical one) infinite is the designation we give to things that are immeasurable. Infinite means "not finite" or "not measurable". Thus neither is knowingly bigger or smaller than the other because they have no measurable length or size. Both in essence have no distance, but the real distinction between the two is that a ray extends or "moves" (for lack of a better term) in one direction, while a line extends in two directions (i.e. movement to the right only as opposed to left and right simultaneously). Infinity is not truly a number, but a concept of something being limitless.
No because a ray only stretches in one way a line stretches in both.
An infinite ray is one half of an infinite line. So that means an infinite line isn't equal to an infinite ray.
No because an infinite line is going to go forever in both directions and a infinite ray will go forever in only one direction.
I guess no because a line doesn't have an end or starting point and a ray does so the line must be longer
my guess is that the line would be longer, because while the ray would go infinite in one direction, the line would go infinite in both directions making the line longer. that is a really good question.
No because infinite line has no starting or ending point where an infinite ray has an starting point.
No because a line is different from a ray
a ray extends in only 1 direction, but a line extends in both directions. So an infinite ray would be half of an infinite line because a ray is one direction, or half of a line
It's actually simple 1 DOES NOT = 1/2
here:
1≠ 1/2
here:
1≠ 1/2
Well actually the line would be longer,because some infinitys are bigger than others.
Ex.:parts of whole numbers such as 1/8 1/3 1/4 and many others.
Ex.:parts of whole numbers such as 1/8 1/3 1/4 and many others.
what's the point _
What is the difference of a ray line segment and a line?
A line segment connects two points and stops at those two points.
A ray starts at a point and continues forever in one direction.
A line continues forever in both directions.
A ray starts at a point and continues forever in one direction.
A line continues forever in both directions.
A ray has a starting point but goes in one direction with no end. A line segment has a starting point and an ending point. A line has neither has a starting or an ending point and goes in both directions.
basically, the difference lies in the start and end points.
a line segment has BOTH a starting point and an end point.
a ray has ONLY a starting point.
a line has NEITHER a starting nor an end point
a line segment has BOTH a starting point and an end point.
a ray has ONLY a starting point.
a line has NEITHER a starting nor an end point
if you watched the video you would understand
A line segment has two end points,ray has one end pint while line has no any end point
A line segment has two end points however a ray has one end point and the other side goes on forever think of it as the suns rays and a line continues in both directions forever with no endpoints! Hope this helps! :)
Well, A ray has a starting point but it keeps going on forever...But a Line has neither a starting or a ending pointit keeps going on forever from both sides.
I Agree with Catherine My Vote
A ray starts at a point and then it just keeps going a line has no points and it does not stop and a line has two points a starting point and a ending point
Is the question: what do you get when you subtract a ray from a line?
Wouldn't that leave another ray?
But would you know the starting point of the result ray?
If you don't know the starting point of a ray, is it still a ray?
This is getting into set theory: rays and lines are infinite sets of points.
Wouldn't that leave another ray?
But would you know the starting point of the result ray?
If you don't know the starting point of a ray, is it still a ray?
This is getting into set theory: rays and lines are infinite sets of points.
A ray line segment has a starting point and goes on forever. A line segment has a starting point and an ending point. A line goes on forever on both directions.
So then what is the point of infinite ray and infinite line?
A ray begins at a point and then continues on in one direction like the rays of the sun. An infinite line goes off in both directions. It has no beginning and no ending.... much like a highway has many points you can stop along the way but seems to continue on and on in both directions.
An infinite ray has a starting point, goes off in one direction with no end. An infinite line has no starting or ending point and goes in two directions.
A ray is limited to one direction, and goes on infinitely in that certain direction. On the other hand, a line is not limited to anything concerning the directions on a 2D plane. (You can only go left, right, up, and down on a 2D plane). The point is very controversial. I would personally say that this is just pure geometry. It doesn't need to be practical. We do this just for the sake of understanding. For example, there isn't anything that actually goes on forever in any direction in real life. That is, unless it is light.
An infinite line has no start or nor end. a ray has a start, but goes on forever.
a ray doesn't have a point,it has a thing that looks like this on the end: > . a line doesn't have a point too,only a line segment
considering that, as someone said, half of infinity is still infinity, you would never be able to get to the end represented as an arrow whereas it would actually be possibly to reach the point represented as a dot
To get an geometric figur because geometry is made of points,line segments and strait lines
a ray has one vertex but the line doesnt have a vertex from the both sides it keeps on going from each side.
the main difference between the two is that a ray actually has a starting point, though it doesn't necessarily have an end point, whereas a line has neither a starting nor and end point
ome oh waneo my omg
;)
;)
What is a segment?
A segment(when talking about a line) is only part of a line. Like he said, a line goes on forever but a line segment doesn't. ♥
A line segment is a line in which it has a starting point and an ending point.
a segment directly means a part
so a line segment is a prat of a line
so a line segment is a prat of a line
He explains it in this video: https://www.khanacademy.org/math/geometry/segmentsandangles/intro_euclid/v/languageandnotationofbasicgeometry
Basically, a segment is a line with two endpoints. It doesn't go on forever like a line, and a segment can be part of an infinite line.
Basically, a segment is a line with two endpoints. It doesn't go on forever like a line, and a segment can be part of an infinite line.
You mean a line segment a line segment is a line that has a starting point and an ending point.
Some thing that is divided into two parts.
A line segment is two points on a line on each side.
A segment is nothing but the part of a line.a line extends infinetly whereas a line segment ends at its end points & has finite length.
math41, hes asking if a ray is the same length as a line
look im not a girl! and i doin this for fun ! plus i am kurtzed1, and i ahead of my grade!!!!!
What if the ray was coming from both sides like this:
<ooo>
Would this be a ray or a line?
<ooo>
Would this be a ray or a line?
It would be a line with points on it
that isn't a ray. .> ray
It's a line. <> line
It's a line. <> line
A Ray would never come from both sides so yes it is a line.
Set of infinite points which they are collinear
what is the difference between a ray segment and a line?
A ray has one endpoint and travels in one direction, while a line is the total opposite of a line segment, having no endpoints and travelling in 2 directions, going into infinity.
A Ray goes on forever in one direction, a line goes on forever in both
A ray segment has somewhere to stop. A line goes in both directions and does not end.
a ray goes on in one direction,a line never stops, and a line segment has two ends
what are skew lines
In other words, you can only have skew lines in 3 or more dimensions, because in 2D plane geometry, lines are either parallel or intersecting, but not both and not neither.
They are not parallel and they never meet
at 1:49 in the video, it said that a ray had a well defined starting point? What did they mean? Did they mean the little arrow on the end?
A line is a series of points which keep growing from both ends. A line segment is a portion of line with two end points. A ray is a line which has got one end point. The open end point is infinite.
Thanks
Thanks
do rays relate to line segments?
I don't think so! Rays only have one end point, line segments have two end points in which do not go in either direction, and Rays on the other hand go on forever in only one direction because Rays only have one end point!
Rays do relate with line segments. Line segments have at two points in which go on forever in both directions. Rays also have two points, but one point goes forever in a direction and the other point has an endpoint and doesn't extend forever.
can a line also be a ray?
Lines cannot be rays.
Line: Extends forever in two directions
Ray: Extends forever in one direction and has one endpoint
Line Segment: Has two endpoints and doesn't extend forever
Line: Extends forever in two directions
Ray: Extends forever in one direction and has one endpoint
Line Segment: Has two endpoints and doesn't extend forever
We'll yes it can because lines and rays both have end points and go strait
No because a line extends in both directions but a ray extends in only one direction
blah people you guys will become millionaires
if a a ray is infinte but with a starting point does it never come back onto itself? essntialy then turning itself into a line?
Well that cant happen because a ray goes on in one direction for ever, and a line goes on for 2 directions forever.
Well, I sort of disagree. It's exactly the fact that a ray is straight that means it WILL come back to itself, since spacetime is 3dimensional.
how can you remember the segments more easily
A segment is not infinite and has 2 endpoints.
At 2:33 they say that the figure is a line. But two endpoints are given, so it doesn't make sense for it to be a line and not a line segment.
It's useful to focus on the arrows  at both ends  that tells us, "YES" it can be a line.
(In the video around 1:00 minute, when Sal sketched a line... I think he should sketch two points along the line, however, he was busy emphasizing those arrows at each end to show it is a line.)
It is good that you saw that it seems to represent a line segment, because the two points there, show a segment within the line. (If the question was, can this represent a LINE SEGMENT? it would be right to say, YES.)
A LINE is defined by two points (where any point has a location) and the line does NOT STOP at either point, so two "arrows" in the sketch always means "this is a line."
Two points A and C and the sketch extends with lines and arrows away from both of two points, can correctly be identified as line segment AC, ray AC, ray CA, and line AC (or line CA).
(In the video around 1:00 minute, when Sal sketched a line... I think he should sketch two points along the line, however, he was busy emphasizing those arrows at each end to show it is a line.)
It is good that you saw that it seems to represent a line segment, because the two points there, show a segment within the line. (If the question was, can this represent a LINE SEGMENT? it would be right to say, YES.)
A LINE is defined by two points (where any point has a location) and the line does NOT STOP at either point, so two "arrows" in the sketch always means "this is a line."
Two points A and C and the sketch extends with lines and arrows away from both of two points, can correctly be identified as line segment AC, ray AC, ray CA, and line AC (or line CA).
nowadays why do people call line segments ,lines
In a conversation outside a math classroom, "line" is descriptive enough, But math users like to be precise.
Why would there be line segments inside a line? I thought It was only part of a line and it wouldn't be inside
If there are four points on a line, there are nine different segments. Think of each little space between the points as a segment by itself. All the other segments create other segments, and each single segment can be used as many times as the patterns require. It's the same basic principle as those "Jim has three shirts and three pairs of pants. How many combinations are there?' questions.
Hope this helps and I didn't confuse you!
Hope this helps and I didn't confuse you!
would the steps to finding the answer to these problems, always be the same?
Is there such thing as a acute line segment
No, "acute" only applies to angles that are smaller than 90 degrees.
Angles are related to line segments because, two segments, that share one point, are the formation of an angle.
Even though I think I know the answer,why can't an infinite line and an infinite ray be the same?
So Is the universe a ray,line or line segment?
The universe is a plane. Like a plane, it goes on forever and ever.
A universe is the universe.
So what is the difference between a ray and a line?
A line goes on forever in both directions. A ray has a starting point, then goes on forever in one direction, kind of like a flashlight beam.
What are the similarities and differences between a line and a line segment?
A line segment is a portion of a line that has a finite length.
Does a line have to have arrows at the end?
no:) as long as you don't put endpoints on it, you can leave the sides open.
__________________
^see that still counts as a line cause it has no endpoints.
__________________
^see that still counts as a line cause it has no endpoints.
wouldnt two rays be equally long
Are lines and rays associated?
Sal Just a side note, if you play the video," recognizing lines"in 4th grade, and add captions, it talks about beer and counting Koreans, I think the computer takes what your saying and mishears it.
would an infinite line and an infinite ray be equally long?
Infinity is infinity. So yes, they would be equally long. Imagine that a ray has a length of infinity. Then imagine a line that has a length of infinity. In theory, they both have lengths of infinity and the line cannot be longer than the ray. Now, if 'infinity' were a normal number, then the line would be twice as long as the ray. But, as I said, infinity is infinity, so in both cases they are extending forever. Hope this helps!
P.S.: This is fun to think about, isn't it?!
P.S.: This is fun to think about, isn't it?!
infinite means that it does not end witch means that you can not tellhow long it is
how much time does it take to make one of your supreme videos
What happens if you tell the difference?
what's the difference between an infinite ray and a ray?
If a ray went infinitely around the Earth, would the end of the ray that keeps going meet up with the other end and become a line?
What is described in the question above, is a curve, and it is not in a single direction like a ray has to be in a single direction. A ray can not curve around Earth, a ray can start at Earth and extend to space. Curves, are never rays, or lines, in geometry definitions. A ray can never meet the start point. Also, a line can not be defined as in the question, as something that goes around and meets the starting point, a line can only go infinitely along in directions away from one point, never meeting up "end to end."
Your question is so important because it hints that you are thinking about the idea of a "curved ray" (or "curved line") and you will have a better time with calculus, because you are thinking about "curved lines".
To be certain about solving geometry problems it's important to be certain that a ray is described by an startpoint and a single direction, not a curve. A general example is, think of the ray of light (like from a laser) it's got a start point, and goes in a single direction  a ray of light.
(A "curved line" is  mathematically  made of teeny segments connected point to point. Here you are entering into calculus, where the teeny segments get cut up teenier and teenier.)
Hope that helps.
Your question is so important because it hints that you are thinking about the idea of a "curved ray" (or "curved line") and you will have a better time with calculus, because you are thinking about "curved lines".
To be certain about solving geometry problems it's important to be certain that a ray is described by an startpoint and a single direction, not a curve. A general example is, think of the ray of light (like from a laser) it's got a start point, and goes in a single direction  a ray of light.
(A "curved line" is  mathematically  made of teeny segments connected point to point. Here you are entering into calculus, where the teeny segments get cut up teenier and teenier.)
Hope that helps.
Can someone make this a little more simple please?
What is the difference between a line and line segment? (Curious)
A line goes out to infinity in both directions. A line segment ends and has a finite length.
What If I were to draw a line around the circumference of a sphere for example, the equator. Do I have a line or a line segment?
If a line segment has a starting point and an ending point, and a ray has a starting point but no ending point, and a line has no starting point or ending point, what would you call something with an ending point but no starting point?
The socalled "Endingpoint" would be thought of as the starting point. Around 1:40 ish, Sal explains the ray, which your question directly relates to. A ray does have a starting point, but no ending point. Ray = infinite. Good question, though! Hope this helps!
Well, think about it visually. We have a line. We know where the ending point is. But where is the starting point? We go on and on in one direction, looking for a starting point. Let's say we can't find ANY starting point at all. That means there is no starting point. But now, look, what have we made in our search for a starting point (in one direction) ? A ray! So, both a line with a starting point but not an ending point AND a line with an ending point but not a starting point are called a ray. :)
Hope this helped,
Reyrout
Hope this helped,
Reyrout
why did they come up with signs to represent rays, line segments, and lines?
what does collinear mean?
Points that are in order to form a line
Points that lie on the same line are collinear...
•A•BC• Points A,B,and C are collinear...
•A•BC• Points A,B,and C are collinear...
can an acute angle go on forever
Yes, because any angle is made up of a series of lines and if you watched this video you know what a line is...so it does go on forever...that is a great question though...
An angle has two rays, and rays go on forever in one direction. Since an acute angle is a type of angle, yes it does
Yes and no.
An angle is the rotation between two rays. The rays go on forever in one direction, so the angle will be there in that direction forever.
However, the distance between the rays will increase as you get further from the intersection, so this information, by itself, doesn't help very much.
An angle is the rotation between two rays. The rays go on forever in one direction, so the angle will be there in that direction forever.
However, the distance between the rays will increase as you get further from the intersection, so this information, by itself, doesn't help very much.
Yes, because the LINES in the angle are, as explained in this video, infinite. They go on forever.
what is the difference between a line segment and a line
A line segment is a segment of a line, also known as a section of a line. They are made up of two points on each end of the segment, with no arrows. A line is a straight mark that consists of two points aswell, but they always have to have the arrows on the ends of the line. A line can go on virtually infinately,since it has those little arrows on the end.
Grocery stores go on for EVER for KIDS!
no they don,t grocery stores start at one end and end at another.
that is called a segment line
that is called a segment line
well it feels like it because our parents need to go EVERY WHERE in the store
Sal mentions the fact that very few objects/situations in our lives go on forever and it got me thinking. Say planet Earth has a single road that goes around the circumference of the planet. Does the road go on forever? I appreciate that if you were to drive on it then it would appear to go on forever but ultimately it's just looping over the same locations.
I guess I'm asking if there is a difference between me shooting a rocket into space that will travel in one direction forever (and constantly going through new space) as oppose to a loop which repeats the same physical space.
Just in case I get attacked by moderators (;)) my link is to lines and infinity as mentioned in the video.
I guess I'm asking if there is a difference between me shooting a rocket into space that will travel in one direction forever (and constantly going through new space) as oppose to a loop which repeats the same physical space.
Just in case I get attacked by moderators (;)) my link is to lines and infinity as mentioned in the video.
Nice answer :D.
what is a ray again?
thank you very much
How do u find the ray segment of a line
I'm not sure what your question means. Could you explain further?
What does congruent mean?
If infinity is forever does that mean half infinity is infinite to
The short answer is no, because infinity isn't really a number
The long answer is in set theory. If you have a set of all the rational numbers (From infinity through +infinity (Excluding irrationals)) and a set of all the REAL numbers. From (+infinity to infinity) the two sets are both infinite but different sizes.
As an interesting aside, the set of positive numbers is the same size as the set of negative and positive numbers, which can be shown by a proof that is rather complicated and long to type out here.
The long answer is in set theory. If you have a set of all the rational numbers (From infinity through +infinity (Excluding irrationals)) and a set of all the REAL numbers. From (+infinity to infinity) the two sets are both infinite but different sizes.
As an interesting aside, the set of positive numbers is the same size as the set of negative and positive numbers, which can be shown by a proof that is rather complicated and long to type out here.
would an infinite line and an infinite ray be equally long? That's my question.
Yes, a line and a ray are the same length  both are infinite. I know that common sense would appear to suggest that the line is twice as long, but they are indeed the same length  the line's infinity is not bigger than the ray's infinity!
Where can you find a video about collinear and coplanar lines?
What is a coplanar?
"Coplanar" just means "on the same plane". If you have a bunch of rays and lines, but they're all on the same plane, they're "coplanar".
Wait,so a line is a endless line?
Correct. A line never ends. You might say "but we see lines end all the time when drawing!" well, those are line _segments_ and not lines. In math, they're signified using dots on either side. Lines are represented with arrows pointing outwards in the directions they're going.
Is there an easier way to memorize which line, line segment, and ray is which? Like some sort of handy trick...
What is the difference of a ray line segment and a line?
is a ray related to a aray?
no it is not related
so how do i know wat the difference is from fay and linesegment
A ray has an arrow on one end and a line stops at two points. The store on the ray represents it going on forever in that direction.
I hope this helps!
I hope this helps!
Why is a line segment with a ray on one of the points called a ray? Why not call it a line segment?
A line segment has length, which is different from a ray which goes off forever in one direction or a line which goes off forever in both directions.
look at it as if the ray was there first. addition of a line segment of, say, (2,3) magnitude to the starting point of the ray sort of extends or "pulls back" that starting point. the ray still remains a ray, it's just that if the original starting point was, say, (2,3), then the new starting point would be (0,0).... or something like that.
hope i explained it clearly
hope i explained it clearly
What is an example of a ray?
A ray is line going off and never stopping like an arrow.
what is the difference between a line and a ray?
A line has no endpoints, it goes on forever in two directions.
A ray has one endpoint (which you may think of as its beginning) and then goes on forever in one direction.
A line segment has two endpoints, it does not go on forever at all. Of the three, only the line segment has a finite length.
All three of these, the line, the ray, and the line segment, are perfectly straight without any curving at all.
A ray has one endpoint (which you may think of as its beginning) and then goes on forever in one direction.
A line segment has two endpoints, it does not go on forever at all. Of the three, only the line segment has a finite length.
All three of these, the line, the ray, and the line segment, are perfectly straight without any curving at all.
A line goes on in two directions, whereas a ray goes on in only one direction.
can a ray go on forever
Yes! Actually a ray can go on forever even though it is going in only one direction.
What is the difference between rays, lines and line segments?
So is a circle a line or a ray?
Neither. Lines and rays are straight, and a circle is not.
how to take a test in this stuff
Can a ray be named after a single point(origin) or is it necessary that it should pass through another point, also if a ray is passing through three points or more
for example : a ray starting at point A passing through point B further through point C and the ray is named as Ray AB can it also be called Ray BC?
for example : a ray starting at point A passing through point B further through point C and the ray is named as Ray AB can it also be called Ray BC?
A ray needs to have two points. Either name is acceptable.
hello, I am a 14yr old high school student who needs help in geometry.my questions, if RS=15 and ST=9, then RS=
Is there a way where the line on a ray can be in a specific way? like left or right?
yes, if the arrow is on the left side, it goes infinently to the left, if the arrow is on the right, it goes infinently right, and so on.
How do you find intersections? I forgot...
In this video you explicity state that lines and rays use arrows to denote they continue in both or one direction, respectively. Is this a universal notation used in Geometry? In the exercise following this video, none of the lines or rays have arrows on them and the correct answers do not use the same conventions as demonstrated in this vido.
If rays have only one direction then why is the starting point of a ray called an "endpoint" when it should be called "startpoint" ? lol. The drawing line exercise after this video is so confusing when they use that terminology because ray AB is not the same as ray BA even though they have the same points.
can a line be a ray
But you could have a line and name a certain part of it as a ray:
<==========A===========B===========>
Pretend that's a line with two points on it, A and B.
You could call it "line AB" that goes on forever in both directions, but you could also say that there are rays in there, like "ray AB" that starts at A, goes through B, and then goes on forever in one direction.
<==========A===========B===========>
Pretend that's a line with two points on it, A and B.
You could call it "line AB" that goes on forever in both directions, but you could also say that there are rays in there, like "ray AB" that starts at A, goes through B, and then goes on forever in one direction.
No, a ray has on end point and continues only in one direction whereas a line has no end points and continues to two directions.
how do you identify rays and lines . they both look same
Lines extend forever in both directions. It looks something like this:
<>
The arrows on each ends indicate that the line keeps on going in both directions, infinitely.
A ray starts off at a point but extends forever in the other direction, or has no end point. Something like this:
•>
The dot on the left indicates the ray's starting point, and the arrow shows that the ray extends forever in that direction.
<>
The arrows on each ends indicate that the line keeps on going in both directions, infinitely.
A ray starts off at a point but extends forever in the other direction, or has no end point. Something like this:
•>
The dot on the left indicates the ray's starting point, and the arrow shows that the ray extends forever in that direction.
Why on a line segment, why are there the two arrows as if it's still calling it a line if the two circles weren't there?
What would you use rays and lines for?
so a line segment can go forever, huh? intresting!
No a line segment has a starting and ending point, but a line can go on forever yes
At 0:36 Sal said line segment what does segment mean?
So what does collinear, coplaner mean? Isnt there a video for that? i cant find it.
Can someone please help?
~Darshi Ambani
Can someone please help?
~Darshi Ambani
Collinear means on the same line, and coplanar means on the same plane (:
In the quiz he was taking he said the line with a dot and arrow on each side was a line not a line segment. does this mean that even if a line has two dots on it as long as it has two arrows aswell it is classed as a line and not a line segment?
wouldn't lines of longitude and latitude be examples of a line that never ends since it goes around the world or would lines that over lap themselves have a stopping point?
um.. actually lines of latitude will not be a line it will be a circle because the definition of a line is a figure made of a series of points linked in a sequence and has no ending. Since latitudes have a ending they cannot be called a line.(line technically has no ending and the thing that is a line with a ending is called a line segment)
how do you do this??
E is the midpoint of line DF
DE=2x3, EF=5x24. Solve for x
DE=2x3, EF=5x24. Solve for x
If E is the midpoint then DE= EF so then 2x3=5x24.
Subtract 2x on both sides of the equation to end up with:
3=3x24
Add 24 to both sides of the equation to end up with:
21=3x
Divide 3 to both sides of the equation to end up with:
7=x
Make sure to check by plugging in 7 to all x's.
Hoped this helped! :)
Subtract 2x on both sides of the equation to end up with:
3=3x24
Add 24 to both sides of the equation to end up with:
21=3x
Divide 3 to both sides of the equation to end up with:
7=x
Make sure to check by plugging in 7 to all x's.
Hoped this helped! :)
so hard how do you this i dont really get it.
So do lines go on forever???
Yeppers, He says it in the video (:
So pay more attention... jkjkjjk!
Im not a meany. lolz
So pay more attention... jkjkjjk!
Im not a meany. lolz
how long is a line
Are rays and segments almost the same?
Hmmm..."almost" in definitions is not something mathematicians use...we're kinda anal retentive that way!
BUT, I see where you are coming from. A segment has 2 end points and a finite length. A ray has 1 endpoint and infinite length.
BUT, I see where you are coming from. A segment has 2 end points and a finite length. A ray has 1 endpoint and infinite length.
helping daughter with hon. geom...how do I find the length of the segment when given J(2,4) and K(1,3) for example? Formula?
You would use the distance formula. The formula is the square root of ( (x1x2)^2(y1y2)^2 ), where y1 and x1 are the x and y coordinates of the same point.
why do we have to make it strait?
so its neat and you can read it
Drawing a curve (or angle) in the line, actually makes it a connected segments, and in geometry it's agreed on that "lines" are straight.
Could a line go on forever?
i am not able to understand coplanar points and collinear points and their respective problems
is the line segment AB = to AB
I love this video but can a line go and retrace it's steps?
its like a circle
woudnt that be a new line?
No they can't. That doesn't even make any sense.
My math textbook asks "In how many points can two distinct lines at the most intersect?" and the answer says one. Wouldn't the answer be infinite because a line passes through infinite points?
so if line and line segments and rays and so measuring segment > but the ray to the line
Why in the quiz he was taking it had dots (indicating a beginning and ending ) and arrows (showing it goes on forever) ? 2:29 . How would I know whether it is a line segment line or ray?
why always a intersecting line or a parllel line be in can be always called in line?
why cant we call it in a line segment? for ex: parllel linesegment?
why cant we call it in a line segment? for ex: parllel linesegment?