Q21 of 78 Page 13

Mark the correct alternative in the following:

The diameter of a circle is increasing at the rate of 1cm/sec. When its radius is π, the rate of increase of its area is


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

A(r)=πr2 – (1)


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


Differentiating (1) with respect to t, we get




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