If the area of a circle is 100pi square feet, find its circumference. Select the correct option
A) 65 pi feet
B) 20 pi feet
C) 42 pi feet
D) 18 pi feet
E) 64 pi feet
The area is given by pi * r * r. Hence   pi * r *r = 100 pi   r *r = 100 ; hence r = 10 feet   The circumference is given by   2 *pi *r = 2 * pi * 10 = 20 pi feet   correct answer 20 pi feet
<result>B</result>
If the area of a circle is 100pi square feet, find its circumference.