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# Polyhedron

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A **polyhedron** (one polyhedron, many *polyhedra*, or *polyhedrons*) is a geometrical shape. It is a 3D shape with flat faces, and straight edges. Usually it is defined by the number of faces, or edges.

Mathematicians do not agree on what makes a polyhedron. They do agree that there are five Platonic solids.

## Naming

Usually, polyhedra are named by the number of faces they have. The first polyhedra are the tetrahedron, which is made of four triangles, pentahedron (five faces, can look like a four-sided pyramid), hexahedron (six faces, a cube if it is regular), heptahedron (seven faces) and octahedron (eight faces). Prisms, pyramids and other shapes can also be named according to how many faces they have.

## Other websites

- Eric W. Weisstein,
*Polyhedron*at MathWorld. - Making Polyhedra
- Polyhedra Pages
- Stella: Polyhedron Navigator – Software for exploring polyhedra and printing nets for their physical construction. Includes uniform polyhedra, stellations, compounds, Johnson solids, etc.
- The Uniform Polyhedra
- Virtual Reality Polyhedra – The Encyclopedia of Polyhedra
- Paper Models of Polyhedra Many links
- Paper Models of Uniform (and other) Polyhedra
- Interactive 3D polyhedra in Java
- World of Polyhedra – Comprehensive polyhedra in flash applet, showing vertices and edges (but not shaded faces)
- Polyhedra software, die-cast models, and posters
- Electronic Geometry Models – Contains a peer reviewed selection of polyhedra with unusual properties
- Symmetry, Crystals and Polyhedra
- uniform solution for uniform polyhedra by Dr. Zvi Har'El
- Java applet with the use of kaleido
- Origami Polyhedra – Models made with Modular Origami
- Polyhedra Collection – Various virtual and physical polyhedra models