if the area of a circle is 16 pi square feet , find its circumference .
"the area is given by pi * r * r . hence pi * r * r = 16 pi r * r = 16 ; hence r = 16 feet the circumference is given by 2 * pi * r = 2 * pi * 4 = 8 pi feet correct answer a"
circumface(sqrt(16))