Question

A circle has a cirumference of 37 5/7 inches. What is its area? use 22/7 for pi

Answer 1

let's firstly convert tyhe mixed fraction to an improper fraction.

`\stackrel{mixed}{37(5)/(7)}\implies \cfrac{37\cdot 7+5}{7}\implies \stackrel{improper}{\cfrac{264}{7}} \\\\[-0.35em] ~\dotfill\\\\ \textit{circumference of a circle}\\\\ C=2\pi r ~~ \begin{cases} r=radius\\[-0.5em] \hrulefill\\ C=(264)/(7) \end{cases}\implies \cfrac{264}{7}=2\pi r\implies \cfrac{264}{7}=2\cdot \cfrac{22}{7}\cdot r \\\\\\ \cfrac{264}{7}=\cfrac{44r}{7}\implies 264=44r\implies \cfrac{264}{44}=r\implies 6=r \\\\[-0.35em] ~\dotfill`

`\textit{area of a circle}\\\\ A=\pi r^2 ~~ \begin{cases} r=radius\\[-0.5em] \hrulefill\\ r=6 \end{cases}\implies A=\pi (6)^2\implies A=\cfrac{22}{7}\cdot 6^2 \\\\\\ A=\cfrac{22}{7}\cdot 36\implies A=\cfrac{792}{7}\implies A=113(1)/(7)`