The radius of a circle is increasing at a rate of 2.5 cm/sec. Find the rate of increase of the area of the circle when its radius is 5cm.

The radius of a circle is increasing at the rate of 0.7 cm/s. What is the rate of increase of its circumference?

The radius of a circle is increasing uniformly at the rate of 3 cm/s. Find the rate at which the area of the circle is increasing when the radius is 10 cm.

If the radius of a circle changes at a uniform rate of 2 cm/s, find the rate of change of area of the circle, at the instant when the radius is 20 cm.

The length of each side of an equilateral triangle increases at the rate of 2cm/sec. Find the rate of increase of the area of the triangle, when the length of each sides is 10cm.

Find the rate of change of the area of a circle with respect to its radius r when r=7cm .

The radius of a circle increases at the rate of (1)/(pi) . Find the rate of change of its (i) circumference and (ii) area when its radius is 2 units.

Find the rate of change of the area of a circle with respect to its radius r when r=12cm .

The radius of an air bubble is increasing at the rate of (1)/(2) cm/s. At what rate is the volume of the bubble increasing when the radius is 1 cm?

The radius of a circle is increased by 2cm from 5 cm to 7 cm . What is the percentage change in area of the circle ?

If the rate of increasae of the side of a squre is 1 cm/sec , the rate of increase of the area of the square when its side 2 cm, is