Exercise 33

The formula

\begin{equation*} A=\frac{1}{2}\,r\,n\,s \end{equation*}

gives the area of a regular polygon with side length \(s\text{,}\) number of sides \(n\) and, apothem \(r\text{.}\) (The apothem is the distance from the center of the polygon to one of its sides.)

What is the area of a regular pentagon with \(s= {90\ {\rm in}}\) and \(r={82\ {\rm in}}\text{?}\)

The area is .