SOLUTION: how do i solve this problem?? "if a circle has an area of 81 pi inches squared what is the circumference. leave your answer in terms of pi."

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Question 426383: how do i solve this problem??
"if a circle has an area of 81 pi inches squared what is the circumference. leave your answer in terms of pi."

Found 2 solutions by mananth, ikleyn:
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
pir^2= 81pi the area
r^2= 81pi/pi
r^2=81
r=9
2pir = circumference
2*8*pi = circumference
16pi = circumference

Answer by ikleyn(53595) About Me  (Show Source):
You can put this solution on YOUR website!
.
how do i solve this problem??
"if a circle has an area of 81 pi inches squared what is the circumference. leave your answer in terms of pi."
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        The solution in the post by @mananth is incorrect.
        I came to bring a correct solution.


pi%2Ar%5E2 = 81%2Api,  the area

r%5E2 = 81%2Api%2Fpi

r%5E2 = 81

r = sqrt%2881%29 = 9

2pi%2Ar = circumference

2%2A9%2Api = circumference

18%2Api = circumference.    ANSWER

Solved correctly.