Q. 173.9( 22 Votes )

The rate of change of the area of a circle with respect to its radius r at r = 6 cm is
A. 10π

B. 12π

C. 8π

D. 11π

Answer :

We know that area of a circle (A) is A = πr2


Then, Rate of change of the area with respect to its radius is given by,



When r = 6cm


Then


Therefore, the area of the circle is changing at the rate of 12πcm2/s when its radius is 6cm.

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