Further MathematicsDifferentiationWAEC
The radius of a circle increases at 2 cm/s. How fast is the area increasing when the radius is 5 cm?
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Answer: A. 20π cm²/s
dA/dt = 2πr × dr/dt = 2π × 5 × 2 = 20π cm²/s.
An AdmitMe practice question, written for the WAEC syllabus. Not an official past question.