The radius of a circle increases at $0.2\text{ cm/s}$. Find the rate of increase of its area when

Question

The radius of a circle increases at $0.2\text{ cm/s}$. Find the rate of increase of its area when the radius is $5\text{ cm}$.

Accepted Answer

$\frac{\mathrm{d}A}{\mathrm{d}t}=2\pi\text{ cm}^2/\text{s}$.

Differentiation