In a rectangle

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

Problem

In a rectangle, the width is always half of its length. When the length is

20\,\text{cm}

and increasing at

4\,\text{cm\,/s}

, calculate: (a) the rate at which the width is changing; (b) the rate at which the perimeter is increasing at that instant (give your answer in

\text{cm\,/s}