# Blend of 2 pentagonal pyramids

Blend of 2 pentagonal pyramids
Rank3
TypeOrbiform
SpaceSpherical
Notation
Bowers style acronymIfbah
Elements
Faces2+4 triangles, 2 pentagons
Edges2+4+4+4
Vertices2+2+4
Measures (edge length 1)
Circumradius${\displaystyle \sqrt{\frac{5+\sqrt{5}}{8}} \approx 0.95106}$
Number of external pieces10
Level of complexity16
Related polytopes
ConjugateBlend of 2 pentagrammic pyramids
Abstract & topological properties
Flag count56
Euler characteristic2
OrientableYes
Genus0
Properties
SymmetryK2×I, order 4
ConvexNo
NatureTame

The blend of 2 pentagonal pyramids, or ifbah, is an orbiform polyhedron. It consists of 6 triangles and 2 pentagons. It is a faceting of the icosahedron, and as its name suggests, it can be formed by blending two pentagonal pyramids together such that they share an edge and the two faces adjacent to this edge.

It appears as a cell of the dodecahedral extended double antiprism.

## Vertex coordinates

The vertices of a blend of 2 pentagonal pyramids of edge length 1 are:

• ${\displaystyle \left(\pm\frac{1+\sqrt{5}}{4},\,0,\,\pm\frac{1}{2}\right),}$
• ${\displaystyle \left(\pm\frac{1}{2},\,\frac{1+\sqrt{5}}{4},\,0\right),}$
• ${\displaystyle \left(0,\,\frac{1}{2},\,\pm\frac{1+\sqrt{5}}{4}\right).}$