I need help, How do u find the circumference with the given radius?

The circumference given the radius can be found using C = 2πr C is the circumference r is the radius

who else is studying in their summer break cause i am asian parents

fr bro im in 3rd grade and this topic kind of hard but can get this!

um i really need help with this i keep getting confused with circumference and radius

The circumference is the distance around the circle. In other words, the circle's perimeter. The diameter is a straight line that passes through the center of the circle. The radius is half of the diameter. It starts from a point on the circle, and ends at the center of the circle. Hope this helps!

no it did not help what is 3.14

3.14 is π (pi, and infinite number) rounded to the nearest hundredth.

okay so if to find circumference= 2pir could it just be diameter x pi? To find circumference?

Yes, both ways work. The only reason to use one or the other is if you are only given the number of the radius or if you are only given the number of the diameter.

do you guys have a step by step for the area of the circle because i am not understanding because i am in 7th grade and i need to know more

Imagine you have a round pizza. The area of a circle is like the amount of space inside that pizza. It tells you how much surface area the circle covers. To find the area of a circle, we use a special number called pi, which is approximately 3.14. Pi helps us figure out how much space is inside the circle. The formula to find the area of a circle is: Area = pi times the radius squared. The radius is a line that starts at the center of the circle and goes to the edge. If you cut the circle in half, the radius would be the distance from the center to the edge. To find the area, we need to know the radius. Once we have the radius, we square it by multiplying it by itself. Then, we multiply that squared radius by pi. For example, let's say the radius of a circle is 5 units. We square the radius: 5 x 5 = 25. Then, we multiply the squared radius by pi: 25 x 3.14 = 78.5. So, the area of the circle with a radius of 5 units is 78.5 square units. It means that if you measured the inside of that circle, it would cover an area of 78.5 square units. Remember, the area is a measure of space inside the circle, like the space on a pizza. And we find it using the formula: Area = pi times the radius squared. please upvote if this helps

so the diameter x Pi = my answer? i feel a tad bit lost.

yes C=πd or C=2πr which is radius times 2 times pi

So circumference and diameter are always the same numbers?

_*The circumference is the diameter times pi* (𝝅)._ `*Example*:` ```*If the diameter is 12 then the circumference is 12*𝝅``` 𝝅 *is generally difficult to calculate, since it goes on forever you can write it in terms of* 𝝅 (*12*𝝅). _*You could also times the diameter by 3.14 to estimate it*._ `*Example*:` ```*If the diameter is 12 then the circumference is 37.68*.``` `_*Hope This Helps*!_`

A wet bicycle tire leaves a trace of water on the floor. The tire has a radius of 30, and the bicycle wheel makes 3 full rotations before stopping. How long is the trace of water left on the floor? Round your answer to the nearest I don't get that

Each rotation produces a trace of water with length equal to the wheel’s circumference. Since the radius is 30, the circumference is 2pi*30 = 60pi. So 3 rotations would produce a trace of water with length 3*60pi = 180pi.

Main content

Class 9 (Foundation)

Course: Class 9 (Foundation) > Unit 11

Lesson 1: Circumference of a circle

Radius & diameter from circumference

Name: Radius & diameter from circumference
Uploaded: 2016-01-03T07:18:09Z
Description: Sal finds the radius and diameter of a circle given the circumference.

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Sal finds the radius and diameter of a circle given the circumference.

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hussain313
Posted 4 years ago. Direct link to hussain313's post “I need help, How do u fin...”
I need help, How do u find the circumference with the given radius?
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Answer
- Andrew H.
  Posted 2 years ago. Direct link to Andrew H.'s post “The circumference given t...”
  The circumference given the radius can be found using C = 2πr
  C is the circumference
  r is the radius
  Comment on Andrew H.'s post “The circumference given t...”
  (14 votes)
Gothic_Robot
Posted 5 years ago. Direct link to Gothic_Robot's post “um i really need help wit...”
um i really need help with this i keep getting confused with circumference and radius
Button navigates to signup pageComment on Gothic_Robot's post “um i really need help wit...”
(15 votes)
Answer
- fishyperson100
  Posted 5 years ago. Direct link to fishyperson100's post “The circumference is the ...”
  The circumference is the distance around the circle. In other words, the circle's perimeter.
  
  The diameter is a straight line that passes through the center of the circle.
  
  The radius is half of the diameter. It starts from a point on the circle, and ends at the center of the circle.
  
  Hope this helps!
  Comment on fishyperson100's post “The circumference is the ...”
  (29 votes)
Caleb Klump-winkle211387
Posted 4 years ago. Direct link to Caleb Klump-winkle211387's post “no it did not help what i...”
no it did not help what is 3.14
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(8 votes)
Answer
- Bradley Swalberg
  Posted 4 years ago. Direct link to Bradley Swalberg's post “3.14 is π (pi, and infini...”
  3.14 is π (pi, and infinite number) rounded to the nearest hundredth.
  Comment on Bradley Swalberg's post “3.14 is π (pi, and infini...”
  (14 votes)
pragyarai
Posted 4 months ago. Direct link to pragyarai's post “who else is studying in ...”
who else is studying in their summer break cause i am

asian parents
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(16 votes)
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- Aiden Lai
  Posted 4 months ago. Direct link to Aiden Lai's post “fr bro im in 3rd grade an...”
  fr bro im in 3rd grade and this topic kind of hard but can get this!
  Button navigates to signup page
  (2 votes)
Rafferty, Mason
Posted 4 years ago. Direct link to Rafferty, Mason's post “okay so if to find circum...”
okay so if to find circumference= 2pir could it just be diameter x pi? To find circumference?
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(7 votes)
Answer
- Tristan Weglarz
  Posted 3 years ago. Direct link to Tristan Weglarz's post “Yes, both ways work. The ...”
  Yes, both ways work. The only reason to use one or the other is if you are only given the number of the radius or if you are only given the number of the diameter.
  Comment on Tristan Weglarz's post “Yes, both ways work. The ...”
  (4 votes)
jessie simental-banuelos
Posted 7 months ago. Direct link to jessie simental-banuelos's post “do you guys have a step b...”
do you guys have a step by step for the area of the circle because i am not understanding because i am in 7th grade and i need to know more
Button navigates to signup pageComment on jessie simental-banuelos's post “do you guys have a step b...”
(6 votes)
Answer
- Chise Bugeer
  Posted 5 months ago. Direct link to Chise Bugeer's post “Imagine you have a round ...”
  Imagine you have a round pizza. The area of a circle is like the amount of space inside that pizza. It tells you how much surface area the circle covers.
  
  To find the area of a circle, we use a special number called pi, which is approximately 3.14. Pi helps us figure out how much space is inside the circle.
  
  The formula to find the area of a circle is: Area = pi times the radius squared.
  
  The radius is a line that starts at the center of the circle and goes to the edge. If you cut the circle in half, the radius would be the distance from the center to the edge.
  
  To find the area, we need to know the radius. Once we have the radius, we square it by multiplying it by itself. Then, we multiply that squared radius by pi.
  
  For example, let's say the radius of a circle is 5 units. We square the radius: 5 x 5 = 25. Then, we multiply the squared radius by pi: 25 x 3.14 = 78.5.
  
  So, the area of the circle with a radius of 5 units is 78.5 square units. It means that if you measured the inside of that circle, it would cover an area of 78.5 square units.
  
  Remember, the area is a measure of space inside the circle, like the space on a pizza. And we find it using the formula: Area = pi times the radius squared. please upvote if this helps
  Comment on Chise Bugeer's post “Imagine you have a round ...”
  (7 votes)
BrickBoyo
Posted 4 years ago. Direct link to BrickBoyo's post “so the diameter x Pi = my...”
so the diameter x Pi = my answer? i feel a tad bit lost.
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(5 votes)
Answer
- David Severin
  Posted 4 years ago. Direct link to David Severin's post “yes C=πd or C=2πr which i...”
  yes C=πd or C=2πr which is radius times 2 times pi
  Comment on David Severin's post “yes C=πd or C=2πr which i...”
  (6 votes)
Noah
Posted 4 years ago. Direct link to Noah's post “A wet bicycle tire leaves...”
A wet bicycle tire leaves a trace of water on the floor. The tire has a radius of 30, and the bicycle wheel makes 3 full rotations before stopping.
How long is the trace of water left on the floor?
Round your answer to the nearest

I don't get that
Button navigates to signup pageComment on Noah's post “A wet bicycle tire leaves...”
(3 votes)
Answer
- Ian Pulizzotto
  Posted 4 years ago. Direct link to Ian Pulizzotto's post “Each rotation produces a ...”
  Each rotation produces a trace of water with length equal to the wheel’s circumference. Since the radius is 30, the circumference is 2pi*30 = 60pi.
  
  So 3 rotations would produce a trace of water with length 3*60pi = 180pi.
  Comment on Ian Pulizzotto's post “Each rotation produces a ...”
  (6 votes)
Rishita
Posted a year ago. Direct link to Rishita's post “So circumference and diam...”
So circumference and diameter are always the same numbers?
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(4 votes)
Answer
- 𝓝𝓪𝓻𝔀𝓱𝓪𝓵
  Posted a year ago. Direct link to 𝓝𝓪𝓻𝔀𝓱𝓪𝓵's post “_*The circumference is th...”
  The circumference is the diameter times pi (𝝅).
  Example:
  If the diameter is 12 then the circumference is 12𝝅
  
  𝝅 is generally difficult to calculate, since it goes on forever you can write it in terms of 𝝅 (12𝝅).
  
  You could also times the diameter by 3.14 to estimate it.
  Example:
  If the diameter is 12 then the circumference is 37.68.
  
  Hope This Helps!
  Button navigates to signup page
  (3 votes)
Gabe.Buck
Posted 7 months ago. Direct link to Gabe.Buck's post “this is super confusing :...”
this is super confusing :|
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(5 votes)
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- savannahbanana
  Posted 5 months ago. Direct link to savannahbanana's post “I know”
  I know
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  (1 vote)

Video transcript

- [Voiceover] Let's say that we know that the circumference of a circle is 49 pi. Based on that, let's see if we can figure out what the radius of that same circle is going to be. And I encourage you, and I'll write equals here. And I encourage you to pause the video, and see if you can figure it out on your own. Let's just draw the circle to help visualize it. I'll just do a hand-drawn circle, clearly not a perfect circle right over here. We know that if its radius is of length r, that the circumference is going to be two pi times r. So, I could write the circumference is equal to two pi times r. In fact, the number pi, the standard definition for it, is just the ratio between the circumference and the diameter of a circle. Now, why is that? Well, if the diameter here is two r, right? We have r and then have another r. We see that the circumference is pi times two r, or we can say that the ratio between the circumference and the diameter, which is the ratio between c and two r, that's just going to be pi. Anyway, I've gone on longer than I need to just to solve this problem. We can go to this original formula here, saying the circumference is two pi times r, and we can just substitute in 49 pi for the circumference. So, we could say 49 pi is going to be equal to two pi times the radius. Now, let's see, we can divide both sides by two pi to solve for r. So, dividing both sides by two pi. On the right-hand side, the two pis cancel out. On the left-hand side, pi divided by pi cancels out. 49 divided by two is 24.5. So, if the circumference is 49 pi whatever units, then the radius is going to be 24.5 of those units. Let's do one more of these. Let's say that we have a circle whose circumference, I'll just say C, is equal to 1600 pi. My question is what is the diameter? The diameter of the circle is equal to what? Just as we said that the circumference could be written as two pi r or as pi times two r, two r is just the diameter. So, we could say that the circumference is equal to pi times the diameter. Once again, that comes out of that traditional definition of pi as the ratio between the circumference and the diameter. You could say that the ratio between the circumference and the diameter is equal to pi. Circles are this very fundamental thing in the universe, and you take the ratio of the circumference and the diameter, you get this magical and mystical number that we see that keeps popping up in mathematics. Anyway, back to the problem. If we say the circumference is 1600 pi, and this is equal to pi times the diameter, we can just divide both sides by pi to get the diameter, which is going to be 1600. The circumference is 1600 pi units, whatever units those are, maybe meters. Then, the diameter is just going to be 1600 of those units, or in this case, maybe meters. And we're all done.