A circular disc has a radius of 10cm. Find the percentage increase in its area if the radius is increased by 2%

Expert Answers
justaguide eNotes educator| Certified Educator

The area of a circle with radius r is equal to `A = pi*r^2` .

Initially the circular disc had a radius of 10 cm. Its area was `pi*10^2 = 100*pi`

When the radius is increased by 2%, the area is `pi*(10*1.02)^2` = `104.04*pi` .

The percentage increase in area is `((104.04*pi - 100*pi)*100)/(100*pi)` = 4.04

The increase in the area is 4.04%