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Plane Geometry Videos 30 videos

ACT Math 1.5 Plane Geometry
297 Views

ACT Math: Plane Geometry Drill 1, Problem 5. If two polygons have the same shape and size, they are what?

ACT Math 3.5 Plane Geometry
394 Views

ACT Math: Plane Geometry Drill 3, Problem 5. How long would it take for the wheel to make two rotations?

ACT Math 4.3 Plane Geometry
361 Views

ACT Math: Plane Geometry Drill 4, Problem 3. What is the measure of each angle in the figure?

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ACT Math 5.1 Plane Geometry 327 Views


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Description:

ACT Math: Plane Geometry Drill 5, Problem 1. What is the area of the circle?

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English Language

Transcript

00:02

Time for your daily dose of Shmoop. This won't hurt a bit.

00:06

A circle has a circumference of 12π. What is the area of the circle?

00:10

And here are your options...

00:15

Okay, so we're given the circumference and we're looking for the area.

00:19

Hopefully, we remember the formula for the circumference of a circle: Diameter times pi

00:19

Hopefully, we remember the formula for the circumference of a circle: Diameter times

00:24

We're told that a circle has a circumference

00:26

of 12 pi...which means the diameter of this circle is 12.

00:31

If the diameter is 12, the radius is exactly half of that... 6.

00:36

The area of a circle is equal to π times radius squared,

00:39

and now that we have the radius, we just have to plug in that value.

00:44

6 squared is 36...so we get 36π as our answer, which is choice C.

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