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9-89.

The United State Department of Defense is located in a building called the Pentagon because it is in the shape of a regular pentagon. Known as “the largest office building in the world,” its exterior edges measure feet.

  1. What is the area of land enclosed by the outer walls of the Pentagon building?

  1. If 1 mile is equal to feet, what is that area in square miles?

A regular pentagon with a side 921 feet.

The pentagon is divided into 5 equal triangles from the center point.

From the center point a perpendicular line is dropped to one of the sides.

Find the area using trigonometric ratios.

The perpendicular line is, h, forming a right angle with the base of the right triangle, 460.5 feet. Angle theta is opposite the side, h.

The interior angles of a regular pentagon measure