If the area of a circle is 81pi square feet, find its circumference.	Choose the correct choice from the following
A) 18 pi feet B) 28 pi feet C) 38 pi feet D) 48 pi feet E) 58 pi feet
The area is given by pi *r* r. Hence   pi * r *r = 81 pi   r * r = 81 ; hence r = 81 feet   The circumference is given by   2 * pi * r = 2 * pi * 9 = 18 pi feet   correct answer 18 pi feet
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If the area of a circle is 81pi square feet, find its circumference.