Quick Question

If the radius of a circle is increasing at a rate of 2 m/s, how fast is the area growing when the radius equals 4 meters?


A = π r2 implies that dA/dt = 2πr dr/dt. Thus, at the instant that r = 4, dA/dt = 2π(4)(2) = 16π.

Close this window to return to the lecture page.