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9
Suppose a forest fire spreads in a circle with radius at rate of 5 per minute. when the radius reaches 200 feet, at what rate is the area of the burning region increasing?
\[\frac{dr}{dt}=5\]\[\frac{dA}{dt}=2 \pi r\frac{dr}{dt}=10 \pi r\]For r=200, the rate is 2000pi
woow same as my asnwer :3 .. thanks man im giving u a medal ; ]