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.

1 answer

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