Question

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

Answer 1

Answer:

Assume that Initial radius = r cm

So, initial circumference = ( 2 pi r) cm

Radius after increasing = (r + 0.7) cm

Circumference = 2 pi ( r + 0.7)

Increase of circumference / sec

= 2 pi ( r + 0.7) - 2 pi r

= 2 pi r + 1.4 pi - 2 pi r

= 1.4 * 22/7

= 0.2 * 22

= 4.4

Increase of circumference

= 4.4 cm / sec

Step-by-step explanation: