- Angles, parallel lines, & transversals
- Parallel & perpendicular lines
- Missing angles with a transversal
- Angle relationships with parallel lines
- Measures of angles formed by a transversal
- Equation practice with angle addition
- Equation practice with angles
Parallel lines are lines in a plane that are always the same distance apart. Parallel lines never intersect. Perpendicular lines are lines that intersect at a right (90 degrees) angle. Created by Sal Khan and Monterey Institute for Technology and Education.
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- Are perpendicular lines intersecting lines,but,intersecting lines not perpendicular lines?(0 votes)
- All perpendicular lines are intersecting lines , but not all intersecting lines are perpendicular lines.(5 votes)
- what are transversals? and how do I use them in Geometry(0 votes)
- Transversals are basically lines intersecting 2 or more lines. There may or may not be employments utilizing this skill, but nevertheless it is very important to learn this while in school (just for the exams at least :)).(10 votes)
- what is that symbol that looks like an upside-down capital T? Does it mean bisects or intercepts or perpendicular?(0 votes)
- The symbol ⊥ is the perpendicular sign - it shows that two lines are perpendicular to each other.
line AB ⊥ line CD.
Hope this helps!(10 votes)
- Couldn't one write that CD is perpendicular to ST and still be correct? This seems a more logical way of stating it, to me.(3 votes)
- Are you referring to what Sal was doing starting at0:39? You are correct that CD is perpendicular to ST, but at the moment Sal was demonstrating that ST is parallel to UV. He simply used CD as a transversal intersecting these two lines to prove that they are indeed parallel, and in the given illustration CD happened to intersect the lines at a 90 degree angle, making it perpendicular to UV and ST. Fundamentally, you are correct.(3 votes)
- So perpendicular line are 90° angle?(5 votes)
- Well sort of, slightly better wording would be perpendicular lines intersect each other at right (90 degree) angles.(1 vote)
- what is the definition of a skew line?(4 votes)
- The definition of a skew line is as follows:
"In three-dimensional geometry, skew lines are two lines that do not intersect and are not parallel." It is important to note the part that says three-dimensional geometry because two lines cannot be skew lines in 2 dimensions. Skew lines are just lines that are in different planes that do not intersect, which fits the definition because two lines being parallel implies they are in the same plane.(0 votes)
- and they ask us to do it with a set square?? Then how?(2 votes)
- squares have equal amount of there sides. so to do that instaed of adding, multiply.(2 votes)
- What does perpendicular mean?(2 votes)
- Do you have a easy math?
Because the hard math is a hard one.
Sometimes it gets very, very harder.(2 votes)
- Can one parallel line be longer than the other?(2 votes)
- Lines are infinitely long. You can say they are equal, or one is bigger than the other, and that would be… somewhat correct, in the world of mathematics.(2 votes)
Identify all sets of parallel and perpendicular lines in the image below. So let's start with the parallel lines. And just as a reminder, two lines are parallel if they're in the same plane, and all of these lines are clearly in the same plane. They're in the plane of the screen you're viewing right now. But they are two lines that are in the same plane that never intersect. And one way to verify, because you can sometimes-- it looks like two lines won't intersect, but you can't just always assume based on how it looks. You really have to have some information given in the diagram or the problem that tells you that they are definitely parallel, that they're definitely never going to intersect. And one of those pieces of information which they give right over here is that they show that line ST and line UV, they both intersect line CD at the exact same angle, at this angle right here. And in particular, it's at a right angle. And if you have two lines that intersect a third line at the same angle-- so these are actually called corresponding angles and they're the same-- if you have two of these corresponding angles the same, then these two lines are parallel. So line ST is parallel to line UV. And we can write it like this. Line ST, we put the arrows on each end of that top bar to say that this is a line, not just a line segment. Line ST is parallel to line UV. And I think that's the only set of parallel lines in this diagram. Yep. Now let's think about perpendicular lines. Perpendicular lines are lines that intersect at a 90-degree angle. So, for example, line ST is perpendicular to line CD. So line ST is perpendicular to line CD. And we know that they intersect at a right angle or at a 90-degree angle because they gave us this little box here which literally means that the measure of this angle is 90 degrees. By the exact same argument, line the UV is perpendicular to CD. Let me make sure I specified these as lines. Line UV is perpendicular to CD. So I did UV, ST, they're perpendicular to CD. And then after that, the only other information where they definitely tell us that two lines are intersecting at right angles are line AB and WX. So AB is definitely perpendicular to WX, line WX. And I think we are done. And one thing to think about, AB and CD, well, they don't even intersect in this diagram. So you can't make any comment about perpendicular, but they're definitely not parallel. You could even imagine that it looks like they're about to intersect. And they give us no information that they intersect the same lines at the same angle. So if somehow they told us that this is a right angle, even though it doesn't look anything like a right angle, then we would have to suspend our judgment based on how it actually looks and say, oh, I guess maybe those things are perpendicular, or maybe these two things are parallel. But they didn't tell us that. And that would actually be bizarre because it looks so not parallel. And actually then this would end up being parallel to other things as well if that was done. It's a good thing that wasn't because it would look very strange. But based on the information they gave us, these are the parallel and the perpendicular lines.