#### 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?

#### Solution

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

*C* = 2π*r.*

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

Hence, the rate of increase of the circumference is `2pi(0.7) = 1.4 pi "cm/s"`

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Solution The Radius of a Circle is Increasing at the Rate of 0.7 Cm/S. What is the Rate of Increase of Its Circumference? Concept: Rate of Change of Bodies Or Quantities.