Question

the radius r of a circle is increasing at a rate of 2 centimeters per minute. find the rate of change of the area when r = 31 centimeters.

Answer 1

Answer: Let r = radius and A = area

dr/dt = 9

A = πr2

dA/dt = 2πr(dr/dt) = 2π(9)(30) = 540π cm2/min

Explanation: