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

Let original radius be r.
Then, according to the questions,
π (r + 1)² - πr² = 22
⇒ π x [(r + 1)² - r²] = 22
⇒ (22/7) x (r + 1 + r ) x (r + 1 - r) = 22
⇒ 2r + 1 = 7
⇒ 2r = 6
∴ r = 6/2 = 3 cm