Q20 of 78 Page 13

Mark the correct alternative in the following:

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


The circumference of a circle, with radius r, is defined as

A(r)=πr2 – (1)


Given that r=12cm, , we have to calculate


Differentiating (1) with respect to t, we get




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