Mathematics

Problem

At the instant when the radius of a circle is

7\,\mathrm{cm}

and increasing at

0.04\,\mathrm{cm/s}

, the rate at which its area is increasing is a)

0.28\pi\,\text{cm}^{2}/\text{s}

14\pi\,\text{cm}^{2}/\text{s}

0.56\,\text{cm}^{2}/\text{s}

0.56\pi\,\text{cm}^{2}/\text{s}