|Dual polyhedron||trigonal bipyramid|
A wedge is a subclass of the prismatoids with the base and opposite ridge in two parallel planes.
- A wedge is a parallelepiped where a face has collapsed into a line.
- A quadrilaterally-based pyramid is a wedge in which one of the edges between two trapezoid faces has collapsed into a point.
For a rectangle based wedge, the volume is
where the base rectangle is a by b, c is the apex edge length parallel to a, and h the height from the base rectangle to the apex edge.
Wedges can be created from decomposition of other polyhedra. For instance, the dodecahedron can be divided into a central cube with 6 wedges covering the cube faces. The orientations of the wedges are such that the triangle and trapezoid faces can connect and form a regular pentagon.
A triangular prism is a special case wedge with the two triangle faces being translationally congruent.
Two obtuse wedges can be formed by bisecting a regular tetrahedron on a plane parallel to two opposite edges.
(Parallel triangle wedge)
Obtuse wedge as a bisected regular tetrahedron
A wedge constructed from 8 triangular faces and 2 squares. It can be seen as a tetrahedron augmented by two square pyramids.
The regular dodecahedron can be decomposed into a central cube and 6 wedges over the 6 square faces.