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## Homework Statement

A stone is thrown into still water, forming ripples which travel from the center of disturbance in the form of circles. If the circumference of the circle which bounds the disturbed area is 10 ft and the circumference is increasing at the rate of 3 ft. per second, how fast is the area increasing ?

## Homework Equations

C=2πr

and

A=π∗r^2

## The Attempt at a Solution

I don't even know how to start this. I'm not supposed to use differentiation but only limiting process.[/B]