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Math III Videos 103 videos

Unit Rate
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Attributes of Circles 6371 Views


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Description:

This video can run circles around other videos about circles. Sir Cumference, of Round Table fame, explains all the properties of… well, circles. Whether you're looking for how the radius relates to the diameter or how to deal with pi (when you’re not eating it, that is), this video covers the basic attributes of our circular friends. Our rotund knight even hits on area and perimeter, too. En garde!

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English Language
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Transcript

00:00

Circles, a la Shmoop. Greetings, members of King Area’s Court!

00:11

I, Sir Cumference, am the one who suggested our great Round Table.

00:17

I know it's caused you all some issues in the past…

00:20

…but switching to a rectangular table would be a big mistake.

00:24

Let me tell you why, dear chaps. First, a circle has no corners, so if we have

00:29

to run suddenly off to battle…

00:31

…or to the loo…

00:32

…we won't hurt ourselves on the corners. While rectangles have two measurements: length

00:37

and width, circles have a radius and a diameter. A circle's radius is the distance from its

00:42

center to the outside…

00:44

… and its diameter is the distance from one side of the circle all the way to the

00:49

opposite side…

00:50

… or, simply put, 2 times its own radius. How much simpler could it be?

00:55

Not yet convinced? Well, the best thing about the Round Table

00:59

is all the pie that comes with it! I don't mean apple or pumpkin pie.

01:04

We can get those at the market. I mean “pi.” 3-point-1-4.

01:07

The Holy Grail of Numbers. For instance, the distance around the circle

01:12

depends on its radius as well as pi!

01:16

We simply plug in 2 times pi times the radius, and we get our Circumference.

01:23

We can also substitute the 2 and the radius with the circle’s diameter to get our circumference.

01:31

But if we're trying to calculate the area of a circle, we'll need pi too.

01:34

Pi times the radius squared will give us the Area of our circle.

01:39

In conclusion, pi makes the world go round. And if the world goes round, why shouldn't

01:45

our table?

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