If the radius of a circle is increased by 1 cm, the area grows by 22 square centimeters. What was the circle's original radius?

Explanation

When the radius increases by 1 cm, the change in area equals π[(r+1)² - r²] = π(2r + 1). Given this increase is 22 cm², solving π(2r + 1) = 22 leads to r ≈ 3 cm.