Question

The US Pentagon is a regular pentagon whose outer walls are each 921 feet in length. Find the area, to the nearest square foot, covered by this enormous building, including the center courtyard

Answer 1

$\bf \qquad \qquad \textit{area of a regular polygon} \\\\\\ A=\cfrac{1}{4}\cdot n\cdot s^2\cdot cot\left( \frac{180}{n} \right)\quad \begin{cases} n= \begin{array}{llll} \textit{number of sides in a polygon}\\ \textit{a pentagon, has PENTA=5 sides} \end{array}\\ s=\textit{length of one of the sides} \end{cases}$