How to Do Perimeter & Circumference

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Perimeter and circumference are two units that measure the distance around and across an object, respectively. Learn how to do perimeter and circumference calculations with help from a mathematics educator in this free video clip.

Part of the Video Series: Mathematics Lessons
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Video Transcript

Hi, I'm Jimmy Chang and we're here to address how to do perimeter and circumference. Now they're both ideas that are very very similar, it's just that circumference applies to only one particular shape whereas the perimeter is a pretty generalized concept. So, when it comes to finding perimeter, we're talking about finding the distance around a two dimensional shape. So I'll just use a rectangle as an illustration and as you now with a rectangle it has two lengths and two widths. Now let's suppose the length was three and the width let's just say was two. So to find the perimeter you simply add all the numbers together, 3 3 = 6, 6 2 = 8, 8 2 = 10 and the perimeter will be 10, whatever units you'll want to use. Now perimeter applies to all sorts of shapes whether it be hexagons, polygons, triangles, squares, rectangles, etc. The one exception though is the one of a circle. Now a circle you can technically find the perimeter of a circle but we don't call that, we call finding the perimeter of a circle the circumference. Now, circumference formula for a circle is C = 2 Pi R, R is the radius of the circle itself. So supposing we have a circle with a certain center that's called 4, once you know the radius of a circle you can plug it in. So to find the circumference of this circle we have C = 2 Pi X let's just say 4 and then we're going to leave the Pi as it is but 2 X 4 =8 so you have 8 Pi and we'll just call it whatever generic units that we want but that means the circumference of this circle is going to be 8 Pi units. Now you can leave it in Pi or if you want to find an approximation just either do 8 Pi on your calculator of if you want to do 3.14 that's perfectly fine too. It's going to be some kind of a number greater than 24 but once you've got the formula, finding the circumference is going to be pretty easy. So I'm Jimmy Chang and there's a couple of illustrations on how to do perimeter and circumference.


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