For a circle whose radius varies with time

MATHEMATICS · Multi-part · AP · Calculus AB · Contextual Applications of Differentiation · Contextual Applications of Differentiation

Problem

For a circle whose radius

r

varies with time

t

, answer the following: (a) Write the expression for the rate of change of its area

A

with respect to time. (b) In one short sentence, explain why your expression involves the factor

\dfrac{dr}{dt}