Question

The ratio of the radius of two circles is 4:5 . Find the ratio of their area.

Answer 1

area of circle = π r^2
r1/r2 = 4/5
ratio of area = π r1^2/π r2^2
= (r1/r2)^2
= 16/25

Answer 2

16/25 or watch the video https://www.khanacademy.org/math/basic-geo/basic-geo-area-and-perimeter/area-circumference-circle/v/circumference-from-area