Question

The area of a circle is increased by 22 cm ^2 when its radius is increased by 1 cm . Find the original radius of the circle

Answer 1

It's simple
Let r be the original radius .
Area of the circle is =π ×r×r = A

Increased radius = r+1
New area = π (r+1) (r+1)=A+22
π×r×r+π+2πr=A+22

As π×r×r=A

A+π(1+2r)=A+22
22÷7(1+2r)=22
1+2r=7
r=3