The radius of a circle is increased by 3 inches which increases the area by 100 inches find the radius of the original circle?

Answer 1

pi*r^2 + 100 = pi * (r+3) *(r+3).

so pi* r^2 + 100 = pi *r^2 + pi *6r + pi *9

so 100 = pi (6r + 9)

take pi as 22/7

then 100 = 132r/7 + 198/7

so 700 = 132r + 198

ie 132 r = 502

r = 3.8, increased to 6.8, giving areas of 45.42 and 145.42 approx.