Mark the correct alternative in the following:

The radius of the base of a cone is increasing at the rate of 3 cm/minute and the altitude is decreasing at the rate of 4 cm/minute. The rate of change of lateral surface when the radius = 7 cm and altitude 24 cm is:


The lateral surface area of a cone, with radius r and height h, is defined as

-(1)


Given that r=7cm, h=24cm, and , we have to calculate


Differentiating (1) with respect to t, we get



Substituting values, we get



Simplifying above equation, we get


1