Pentahedron
Template:Expand Chinese Template:Short description Template:More sources needed Template:For In geometry, a pentahedron (Template:Plural form: pentahedra) is a polyhedron with five faces or sides. There are no face-transitive polyhedra with five sides, and there are two distinct topological types. Notable polyhedra with regular polygon faces are:
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Square pyramid with four triangles and one square.Template:R Pyramids with any quadrilateral base have the same number of faces.
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Triangular prism with three rectangles and two triangular bases.Template:R In the case of a right triangular prism, it is a special case of wedge with connecting parallel edges between triangles; the wedge generally has two triangles and three quadrilateral faces.Template:R Topologically, the triangular frustum is the same polyhedron, but the two triangles are different sizes, and the sides are slanted trapezoids.
The pentahedra can be used as space-filling.Template:R
Concave
An irregular pentahedron can be a non-convex solid: Consider a non-convex (planar) quadrilateral (such as a dart) as the base of the solid, and any point not in the base plane as the apex.
Hosohedron
There is a third topological polyhedral figure with 5 faces, degenerate as a polyhedron: it exists as a spherical tiling of digon faces, called a pentagonal hosohedron with Schläfli symbol {2,5}. It has 2 (antipodal point) vertices, 5 edges, and 5 digonal faces.