Question

The radius of a circular puddle is growing at a rate of 25 cm/sec.

Answer 1

Answer:

Step-by-step explanation:

a)area A=pi r^2

rate of change of area =dA/dt =2 pi r dr/dt

given dr/dt =25 ,r =50

rate of change of area =dA/dt =2 pi *50 *25 =2500pi=7854

area growing 7854 cm2/s

b)area A=pi r^2

rate of change of area =dA/dt =2 pi r dr/dt

given dr/dt =25 ,A =64

pi r^2 =64

=>r =8/√pi

rate of change of area =dA/dt =2 pi *(8/√pi) *25 =400√pi=708.98

area growing 708.98 cm2/s