Mark the correct alternative in the following:
The altitude of a cone is 20 cm and its semi-vertical angle is 30°. If the semi-vertical angle is increasing at the rate of 2° per second, then the radius of the base in increasing at the rate of

Question

Philoid · Accepted Answer

The relation between height h, radius r and semi-vertical angle α is defined by

Given that h=20cm

-(1)

Given that α=30° and , we have to find

Differentiating (1) with respect to t, we get

Substituting values, we get

⇒

Mark the correct alternative in the following:The altitude of a cone is 20 cm and its semi-vertical angle is 30°. If the semi-vertical angle is increasing at the rate of 2° per second, then the radius of the base in increasing at the rate of