# Bifrustum

Set of bifrustums
or
Truncated bipyramids

Example hexagonal bifrustum
Faces 2 n-gons, 2n trapezoids
Edges 5n
Vertices 3n
Symmetry group Dnh, [n,2], (*n22)
Dual polyhedron Elongated bipyramids
Properties convex

An n-agonal bifrustum (or truncated bipyramid) is a polyhedron composed of three parallel planes of n-agons, with the middle plane largest and usually the top and bottom congruent.

It can be constructed as two congruent frusta combined across a plane of symmetry, and also as a bipyramid with the two polar vertices truncated.

They are duals to the family of elongated bipyramids.

## Forms

Three bifrustums are duals to three Johnson solids, J14-16. In general, a n-agonal bifrustum has 2n trapezoids, 2 n-agons, and is dual to the elongated dipyramids.

Triangular bifrustum Square bifrustum Pentagonal bifrustum
6 trapezoids, 2 triangles. Dual to elongated triangular bipyramid, J14 8 trapezoids, 2 squares. Dual to elongated square bipyramid, J15 10 trapezoids, 2 pentagons. Dual to elongated pentagonal bipyramid, J16