The Pentagon is one of the largest office buildings in the world in terms of ground area. The perimeter of the building has the shape of a regular pentagon with each side 921.6 feet long. Find the...

The Pentagon is one of the largest office buildings in the world in terms of ground area. The perimeter of the building has the shape of a regular pentagon with each side 921.6 feet long. Find the area enclosed by the perimeter of the building. Use your knowledge of precalculus to solve the problem, not Google.