1. To see how the surface area of a sphere is derived,
watch the following video:

2. The surface area of a sphere is the area of 4 circles,
A = 4 (Acircle)
A = 4 r2

3. Part G – Surface Area of Spheres
Example: Find the radius (to the nearest unit) of a hemisphere with a total
surface area of 572 cm2.
Equation:
Substitute:
A = ½ of Asphere + Acircle
= ½ (4r2) + r2
= 2r2 + r2
= 3r (simplify)
= 3r2
3 
= r2
= r (sqrt both sides)
r =7
 The radius of the hemisphere is 8 cm.