Question

The surface area of a sphere initially zero increases uniformly at the rate of 26 cm^2/seconds. Find the rate at which the radius is increasing at the end of 2 seconds.

Answer 1

a = 4πr^2
at t=2, a=52, so r=√(13/π)

da/dt = 8πr dr/dt
so, you need

8π√(13/π) dr/dt = 26
dr/dt = 1/4 √(13/π)

Answer 2

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