The radius of a circular plate is increasing at the rate of 0.01 cm/sec. The rate of increase of its area when the radius is 12 cm, is

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KollegeApply · Accepted Answer

0.24 $\pi$ cm2/sec \text { Let r be the radius and A be the area of the circular plate at any timet.Then,} A=$\pi$ r^2 \RightarrowdA/dt=2$\pi$ rdr/dt \RightarrowdA/dt=2$\pi$\left( 12 \right)\left( 0 . 01 \right) \RightarrowdA/dt {=0.24$\pi$ \ cm}^2 /sec

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