Question

The base of the rectangle is changing at the rate of 3in/min. if its height remains constant, determine the rate of change of its perimeter with respect to time?

Answer 1

$\frac{da}{dt}=3in/\min \\b=Const\\P=2a+2b\\\frac{dP}{dt}=2\frac{da}{dt}=6in/\min$