The Total solution for NCERT class 6-12
The radius of a circle is increasing uniformly at the rateof 3 cm/s. Find the rate at which the area of the circle is increasing when theradius is 10 cm.
The area of a circle (A) with radius (r)is given by,
Now, the rate of change of area (A)with respect to time (t) isgiven by,
It is given that,
Thus, when r = 10 cm,
Hence, the rate at which the area of thecircle is increasing when the radius is 10 cm is 60π cm2/s.