Question

What is the radius of a sphere if its surface area is 2,122.64 square inches? (Use 3.14 for .)

11 in.
13 in.
121 in.
169 in.

Answer 1

`\bf \textit{surface area of a sphere}\\\\ SA=4\pi r^2~~ \begin{cases} r=radius\\ ------\\ SA=2122.64 \end{cases}\implies 2122.64=4\pi r^2 \\\\\\ \cfrac{2122.64}{4\pi }=r^2\implies \cfrac{530.66}{\pi }=r^2\implies \sqrt{\cfrac{530.66}{\pi }}=r`

Answer 2

13

Explanation: