ShmoopTube
Where Monty Python meets your 10th grade teacher.
Search Thousands of Shmoop Videos
Plane Geometry Videos 30 videos
ACT Math: Plane Geometry Drill 3, Problem 1. What is the area of the trapezoid shape in the video?
ACT Math: Plane Geometry Drill 1, Problem 5. If two polygons have the same shape and size, they are what?
ACT Math: Plane Geometry Drill 3, Problem 5. How long would it take for the wheel to make two rotations?
ACT Math 5.1 Plane Geometry 327 Views
Share It!
Description:
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.
Related Videos
ACT Math: Plane Geometry Drill 3, Problem 1. What is the area of the trapezoid shape in the video?
ACT Math: Coordinate Geometry Drill 1, Problem 1. Which inequality is expressed by the number line?
ACT Math: Intermediate Algebra: Drill 3, Problem 1. Find the fifth number in the series.
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."