Question

1. Find the rate of change of the area of a circle with respect to its radius r when
(a) r = 3 cm
(b) r= 4 cm
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Answer 1

Answer:

Radius of circle=r

d/a & d/r need to be calculated

area of circle=  r 2π

r = 3cm

r = 4cm

Step-by-step explanation:

Since area is in cm square & radius in cm

da/dr = 8π cm2/cm

Hence the area is increasing at the rate of 8π cm2/cm when r=4cm