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This video can run circles around other videos about circles. Sir Cumference, of Round Table fame, explains all the properties of… well, circles....
Time to learn about the area of a sector. And no, that's not the sector's bedroom with a bumper sticker on the door that reads, "GO AWAY."
ACT Math: Plane Geometry Drill 5, Problem 1. What is the area of the circle?
ACT Math 5.1 Plane Geometry 327 Views
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ACT Math: Plane Geometry Drill 5, Problem 1. What is the area of the circle?
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
Full Transcript
- 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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This video can run circles around other videos about circles. Sir Cumference, of Round Table fame, explains all the properties of… well, circles....
Time to learn about the area of a sector. And no, that's not the sector's bedroom with a bumper sticker on the door that reads, "GO AWAY."