|This is an AoPSWiki Word of the Week for Sep 6-12|
A pyramid is a 3-dimensional geometric solid. It consists of a base that is a polygon and a vertex not on the plane of the polygon. The edges of the pyramid are the sides of the polygonal base together with line segments connected the vertex of the pyramid to each vertex of the polygon.
Some well-known pyramids include the tetrahedron, which has an equilateral triangle for its base and all edges of equal length, and is one of the Platonic solids. Another is the regular square pyramid. Two of these with their bases joined form an octahedron, which is another Platonic solid.
If the base of the pyramid has sides, then the pyramid has edges, vertices, and faces (of which are triangular, and the remaining one is the base).
|AoPSWiki Words of the Week for Sep 6-12|