Pyramid

:See also: Egyptian pyramids, Mesoamerican pyramids, Nubian pyramids.

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An n-sided pyramid is a polyhedron formed by connecting an n-sided polygonal base and a point, called the apex, by n triangular faces (n≥3). In other words, it is a conic solid with polygonal base. When unspecified the base is usually assumed to be square. For a triangular pyramid each face can serve as base, with the opposite vertex as apex. One of the Platonic solids, the tetrahedron, is a triangular pyramid. The square and pentagonal pyramids can also be constructed with all faces regular, and so count among the Johnson solids. All pyramids are self-dual. The volume of a pyramid is V = rac{1}{3} Ah where A is the area of the base and h the height from the base to the apex.

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The geometric centre of a square-sided regular pyramid is located on the symmetry axis, one quarter of the way from the base to the apex.

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If the base is regular and the apex is above the center, the symmetry group of the n-sided pyramid is Cnv of order 2n, except in the case of a regular tetrahedron, which has the larger symmetry group Td of order 24, which has four versions of C3v as subgroups.

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The rotation group is Cn of order n, except in the case of a regular tetrahedron, which has the larger rotation group T of order 12, which has four versions of C3 as subgroups.

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Egyptian pyramids: The pyramids of Egypt, some of which are among the largest man-made constructions ever conceived , constitute one of the most potent and enduring symbols of Ancient Egyptian civilization. Although no ancient Egyptian rulers have been found buried in an Egyptian pyramid, it is generally accepted by m...

Mesoamerican pyramids: Most Ancient Mesoamerican civilisations built pyramid-shaped structures. These were also usually step pyramids, with temples on top – more akin to the ziggurats of Mesopotamia than to the pyramids of Ancient Egypt. The Mesoamerican region's largest pyramid by volume – indeed, the largest...

Nubian pyramids: The area of the Nile valley known as Nubia that lies within present day Sudan was home to three Kushite kingdoms during antiquity: the first with its capital at Kerma (2400–1500 BC), that centred on Napata (1000–300 BC) and, finally, that of Mero? (300 BC–300)....

Pyramid related Images and Photos (experimental)

Pyramid Lake Nevada	Tomato Pyramid	Pyramid Mt. at Sunrise Canada	Pyramid Mt. at Sunrise Canada
Pyramid Ball Wooden Puzzle	Mystic Pyramid Puzzle	Cat Pyramid Treat Toy	Pyramid Moody Gardens Galveston Texas USA
Seven Dwarfs Pyramid Cutout	Transamerica Pyramid San Francisco California USA	Sphinx and Pyramid Egypt	Sphinx and Pyramid at Sunset