SOLUTION: Hi, I have this problem on my Coure Test Review Packet. Its asking me 'What is the area of a circle with the circumference of 18pie?' But I don't understand it. Im not very good

Question 443556: Hi,
I have this problem on my Coure Test Review Packet. Its asking me 'What is the area of a circle with the circumference of 18pie?' But I don't understand it. Im not very good at circles so I don't know how to do it. Please help.
Justice
Answer by richard1234(7193) (Show Source): You can put this solution on YOUR website!
This problem is simply applying the area/circumference formulas for circles. The circumference C is 18pi, so

. This implies r = 9.

Given the area formula

, we replace r with 9 to obtain

The circumference/area formulas are very useful to know. I usually advise knowing how to derive the formulas as well so that it does not become rote memorization. However you probably won't learn the proof of the area/circumference of a circle until you take a calculus course.
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