SOLUTION: Find the perimeter of the square in which a circle of area 81 pi is inscribed. How can I find that? Please show me.

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Question 282552: Find the perimeter of the square in which a circle of area 81 pi is inscribed.
How can I find that? Please show me.
Answer by user_dude2008(1862) About Me  (Show Source):
You can put this solution on YOUR website!
A=81pi ----> 81pi=pi*r^2 ----> 81=r^2 ----> r=9

side length of square = 2*r = 2*9 = 18

Perimeter = 4*18 = 72

Answer: 72