The radius of a circular mirror is increased by 2 inches due to its decorative border. This increases the area by 113 square inches. Find the radius of the mirror without the decorative border. Round to the nearest whole number.

Answer 1

original radius --- r inches
original area = πr^2 inches^2

new radius = x+2
new area = π(r+2)^2

π(r+2)^2 - πr^2 = 113
π(r^2 + 4r + 4) - πr^2 = 113
4πr = 113-4π
r = (113 - 4π)/(4π) = ...

let me know what you get