pyramid (geometry)

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pyr·a·mid / ˈpirəˌmid/ • n. 1. a monumental structure with a square or triangular base and sloping sides that meet in a point at the top, esp. one built of stone as a royal tomb in ancient Egypt. 2. a thing, shape, or graph with such a form: the pyramid of the Matterhorn. ∎  Geom. a polyhedron of which one face is a polygon of any number of sides, and the other faces are triangles with a common vertex: a three-sided pyramid. ∎  a pile of things with such a form: a pyramid of logs. ∎  Anat. a structure of more or less pyramidal form, esp. in the brain or the renal medulla. ∎  an organization or system that is structured with fewer people or things at each level as one approaches the top: the lowest strata of the social pyramid. ∎  a system of financial growth achieved by a small initial investment, with subsequent investments being funded by using unrealized profits as collateral. • v. [tr.] heap or stack in the shape of a pyramid: debt was pyramided on top of unrealistic debt in an orgy of speculation. ∎  achieve a substantial return on (money or property) after making a small initial investment. DERIVATIVES: py·ram·i·dal / piˈramidl/ adj. py·ram·i·dal·ly adv. pyr·a·mid·i·cal / ˌpirəˈmidikəl/ adj. pyr·a·mid·i·cal·ly adv.


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pyramid. Monumental structure with a square base and steep battered triangular sides terminating in an apex. The form was used in Ancient Egypt for funerary structures: celebrated examples are the pyramids at Giza, near Cairo, Egypt (c.2551–c.2472 bc). Other types of pyramid include the stepped form found in both Ancient Egyptian and Meso-American Pre-Columbian architecture, but in the latter region the buildings were temple-platforms rather than tombs. The best-known stepped pyramids are the Ancient Egyptian pyramid at Saqqara, built by Imhotep for King Zoser (c.2630–c.2611 bc), and the temple-pyramids of the Meso-American Aztec and Maya cultures (c. C6–C16). Pyramids often featured in Neo-Classical architecture (Roman pyramids including that of Cestius (c.12 bc) ), and appealed to designers for their stereo-metrical purity of form, thus responding to Laugier's admiration for an architecture that was primitive and pure. Pyramidal compositions were common in funerary monuments from the time of Bernini, and countless C18 examples exist.


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pyramid, in geometry, solid figure bounded by a polygon (the base, or directrix) and the surface generated by a moving line (the generator) passing through a fixed point (vertex) and continually intersecting the perimeter of the polygon. The surface, or lateral faces, of the pyramid are triangles having as a common vertex the vertex of the pyramid; in a regular pyramid the base is a regular polygon and the lateral faces are congruent triangles. The altitude of a pyramid is the perpendicular distance from the vertex to the base. The volume of a pyramid is equal to one third the product of the altitude and the area of the base. The frustum is the portion of a pyramid between the base and a plane parallel to the base cutting the pyramid into two parts.

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pyramid In geometry, solid figure having a polygon as one of its faces (the base), the other faces being triangles with a common vertex. Its volume is one third of the base area times the vertical height.