Question

Surface area of a sphere is pi m^2.If the radius is doubled, find thedifference in area

Answer 1

Given Surface area of a spehere, S = πm²

Also S.A of a sphere = 4πr²

( r = radius of the sphere )

on equating

4πr² = πm²

4r² = m²

(2r)² = m²

r = m/2

Now if radius is doubled, r' = 2r = m

New S.A = S' = 4πr'²

S'= 4πm²

Difference in Surface Areas = S'– S

= 4πm² – πm²

= 3πm²

Hope the solution is clear to you!!