Question

If the area of a circle is 81pi square feet, find its circumference.
A. 18 Pi feet
B. 20 pi feet
C. 35 pi feet
D. 25 pi feet

Answer 1

πr^2=81π,r^2=81 then r=9,2πr=2×π×9=18π

Answer 2

$\textbf {Hey there, here is the solution.}$

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Find radius:

Area = πr²

Given that area = 81π ft²:

πr² = 81π

Divide both side by π:

r² = 81

Square root both sides:

r = 9

Find circumference:

Circumference = 2πr

Circumference = 2π (9)

Circumference = 18π ft

Answer: (A) 18π ft

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⭐$\textbf {Cheers}$⭐