Question

A rock is dropped in a pond, causing circular ripples. The radius increased with a rate 1 foot per second. When the radius is 4 feet, the area is increasing by 8π square feet per second.1. True2. False

Answer 1

Answer:

true

Explanation:

Area = πr²

Differentiating in respect to r

we get,

dA/dr = 2πr

using chain rule,

$\frac{dA}{dt} = \frac{dA}{dr} .\frac{dr}{dt} = 2\pi \frac{dr}{dt}$

since r = 4feet

so ,

2π(4) = 8π