The sum of the areas of two circles is 80 square meters. Find the length of a radius of each circle if one of them is twice as long as the other.



What is the radius of the larger circle?

1 answer

Let the radius of the smaller circle be r, then the radius of the larger circle is 2r.

The area of a circle is given by the formula A = πr^2.

The sum of the areas of the two circles is 80 square meters:

πr^2 + π(2r)^2 = 80
πr^2 + 4πr^2 = 80
5πr^2 = 80
r^2 = 16
r = 4

The radius of the larger circle (2r) would be:
2r = 2(4) = 8

Therefore, the radius of the larger circle is 8 meters.