The radius of a circle is increasing at the rate of 0.7 cm/s. What is the rate of increase of its circumference?

The circumference of a circle (C) with radius (r) is given by

C = 2πr.

Therefore, the rate of change of circumference (C) with respect to time (t) is given by,

(By chain rule)

It is given that.

Hence, the rate of increase of the circumference