Question

if a sphere of diameter has 80 units, the diameter divided by 2, how is the surface area of the resulting sphere affected?

Answer 1

What's the formula for surface area of a sphere?
Is it 4pi(r)^2

Answer 2

i think it is S= 4 pi r^2

Answer 3

(4pi(20)^2)/4pi(40)^2) = (20 x 20)/(20 x 20 x 2 x 2) = 1/4
So the new surface area is 1/4 of the original one

Answer 4

thank you