Triangular prism

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Triangular prism

Type	Semiregular polyhedron
Faces	2 triangles 3 square
Edges	9
Vertices	6
Vertex configuration	3.4.4
Wythoff symbol	2 3 \| 2
Symmetry group	D_3h
Dual	triangular dipyramid
Properties	convex
Vertex Figure

For optical prisms, see Prism (optics).

In geometry, a triangular prism or three-sided prism is a polyhedron made of a triangular base, a translated copy, and 3 faces joining corresponding sides.

If the sides are squares, it is called a uniform polyhedron. In general the sides can be congruent rectangles.

Equivalently, it is a pentahedron of which two faces are parallel, while the surface normals of the other three are in the same plane (which is not necessarily parallel to the base planes). These three faces are parallelograms. All cross-sections parallel to the base faces are the same triangle.

A right triangular prism is semiregular if the base faces are equilateral triangles, and the other three faces are squares.

A general right triangular prism can have rectangular sides.

The dual of a triangular prism is a 3-sided bipyramid.

The symmetry group of a right 3-sided prism with regular base is D_3h of order 12. The rotation group is D₃ of order 6.

The symmetry group does not contain inversion.