Question

The surface area of a sphere is found using the formula SA=4πr^2, where r is the radius. If the surface area of a sphere is 64π square feet, what is the radius, in feet? A. 3 B. 18 C. 1 D. 4

Answer 1

The answer should be d
64pi=4pir^2
cancel the pi
64=4r^2
16=r^2
r=4

Answer 2

$SA = 4 \pi r^{2}$
$64 \pi = 4 \pi r^{2}$
$16= r^{2}$
$r^{2}=16$
 $r=4$ (Answer D)