AP Calculus ABeasymcq1 pt
The radius of a circular puddle is increasing at a rate of 2 cm/s. How fast is the area of the puddle increasing when the radius is 10 cm?
A.20π cm²/s
B.40π cm²/s
C.100π cm²/s
D.200π cm²/s
Explanation
Core Concept
We know that A = πr². Differentiating with respect to time t: dA/dt = 2πr(dr/dt). Given dr/dt = 2 cm/s and r = 10 cm: dA/dt = 2π(10)(2) = 40π cm²/s.
Correct Answer
B40π cm²/s
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