Polyhedron
A polyhedron is a three-dimensional surface composed of at least four flat faces which encloses a region of space. These faces intersect in edges and vertices. Polyhedra are 3-D analogues of polygons. They can be thought of as sets of ordered triples.
Contents
[hide]Classification
Concavity
Polyhedra can be convex or concave]].
Number of sides
Regular polyhedra
They have congruent faces, angles, and edges. Only regular tetrahedra, hexahedra (cubes), octahedra, dodecahedra, and icosahedra exist. (In addition, a sphere could be thought of a polyhedron with an infinite number of faces.)
Common polyhedra
The polyhedra most commonly encountered include:
- tetrahedron - 4 faces
- hexahedron - 6 faces
etc.
Prisms and pyramids can be polyhedra.
Surface area
The surface area of a polyhedron is the sum of its sides.
Volume
Angles
Related figures
- Polyhedral solids are the union of a polyhedron and the space that it encloses.
- Polygons
- Polytopes
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