Sum of angles of a triangle to zero. For a spherical triangle, the sum of the angles is greater than 180° and can be up to 540°. Specifically, the sum of the angles is where "f" is the fraction of the sphere's area which is enclosed by the triangle. Note that spherical geometry does not satisfy several of Euclid's axioms (including the parallel postulate.) Angles between adjacent sides of a triangle are referred to as "interior" angles in Euclidean and other geometries. "Exterior" angles can be also defined, and the Euclidean triangle postulate can be formulated as the exterior angle theorem. One can also consider the
The Pentagon records storage facility at some time after the end of the current war. A minimal amount of steel was used as it was in short supply during World War II. Instead, the Pentagon was built as a reinforced concrete structure, using 680,000 tons of sand dredged from the Potomac River, and a lagoon was created beneath the Pentagon's river entrance. To minimize steel usage, concrete ramps were built rather than installing elevators. Indiana limestone was used for the building's façade. Architectural and structural design work for the Pentagon proceeded simultaneously with construction, with initial drawings provided in early October 1941,