Answer: 81pi
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Explanation:
If the diameter is d = 18, then the radius is half that at r = d/2 = 18/2 = 9
Then that radius is plugged into the circle area formula below
A = pi*r^2
A = pi*9^2
A = pi*81
A = 81pi
If you were to use an approximation like pi = 3.14, then the approximate area would be 81*pi = 81*3.14 = 254.34 mm^2; however, your teacher wants you to write the exact area.
