Question

the area of a circle is 81 pi m^2. what is the circumference, in meters? express your answer in terms of pi.

Answer 1

Answer:    18pi

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Explanation:

The area 81pi square meters leads to the radius 9 meters

Use the formula A = pi*r^2 to see why this is the case. You plug in A = 81pi and solve for r to get r = 9.

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Once you know the radius, you can determine the circumference C

C = 2*pi*r

C = 2*pi*9

C = 2*9*pi

C = 18pi

The circumference is the perimeter, or distance, around the circle.