Pentagon Pentagon In geometry, a pentagon (from the Greek πέντε "pente" and γωνία "gonia", meaning "five" and "angle") is any five-sided polygon or 5-gon. The sum of the internal angles in a simple pentagon is 540°. A pentagon may be simple or self-intersecting. A self-intersecting "regular pentagon" (or "star pentagon") is called a pentagram. A "regular pentagon" has Schläfli symbol {5} and interior angles are 108°. A "regular pentagon" has five lines of reflectional symmetry, and rotational symmetry of order 5 (through 72°, 144°, 216° and 288°). The diagonals of a convex regular pentagon are in the golden ratio to its
The Pentagon Airlines Flight 77 was hijacked and flown into the western side of the building, killing 189 people (59 victims and the five perpetrators on board the airliner, as well as 125 victims in the building), according to the 9/11 Commission Report. It was the first significant foreign attack on Washington's governmental facilities since the city was burned by the British during the War of 1812. The Pentagon is listed on the National Register of Historic Places and is a National Historic Landmark. The Pentagon building spans , and includes an additional as a central courtyard. Starting with the north side