Chapter 9, Problem 3CA

a.

To determine

To check if the statement is correct.

Answer to Problem 3CA

The claim is incorrect

Explanation of Solution

Given information:

  $S=2\pi r^2+2\pi rh$

Calculation:

The given formula is $S=2\pi r^2+2\pi rh$

Taking common,

  $S=2\pi r(r+h)$

Here, it can be seen that to find r , we need r , hence, it is incorrect

b.

To determine

To check if the statement is correct

Answer to Problem 3CA

The claim is correct.

Explanation of Solution

Given information:

  $S=4\pi r^2$

Calculation:

The given formula is $S=4\pi r^2$

Solving for r ,

  $\begin{array}{l}\\ \frac{S}{4\pi }=r^2\end{array}$

Rooting both sides,

  $r=\sqrt{\frac{S}{4\pi }}$

Hence, the claim is correct.