The radius of a circle is increasing at a constant rate of 0.2 cm per second. In terms of the circumference C, what is the rate of change of the area of the circle, in square centimeters per second?

Answer 1

Given: r' = 0.2 cm/sec

Find: A' in terms of C

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SOLUTION:

A = pi*r^2

dA/dt = pi*2r*r'

dA/dt = [2pi*r]*(r')

dA/dt = [ C ]*(0.2)

A' = C*(0.2) cm^2/sec

Answer 2

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