Question

A parabolic listening device is shaped such that the depth of the bowl depends on its radius and can be represented by the curve D(r) = 0.145r2.
What is the radius when the depth is 8 inches? Round to the nearest thousandth of an inch.

Answer 1

Answer:

$\large \boxed{\text{7.428 in}}$

Step-by-step explanation:

$\begin{array}{rcl}D & = & 0.145 r^{2}\\8 & = & 0.145 r^{2}\\55.17 & = & r^{2}\\r & = & \sqrt{55.17}\\& = & \textbf{7.428 in}\\\end{array}\\\text{The radius is \large \boxed{\textbf{7.428 in}} when the depth is 8 in.}$

The graph shows the profile of your parabolic listening device,

Answer 2

The answer is c on edg