# Elongated pentagonal orthobicupola

Elongated pentagonal orthobicupola Rank3
TypeCRF
SpaceSpherical
Notation
Bowers style acronymEpobcu
Coxeter diagramoxxo5xxxx&#xt
Elements
Faces10 triangles, 5+5+10 squares, 2 pentagons
Edges10+10+10+10+20
Vertices10+20
Vertex figures10 isosceles trapezoids, edge lengths 1, 2, (1+5)/2, 2
20 trapezoids, edge lengths 1, 2, 2, 2
Measures (edge length 1)
Volume$\frac{10+8\sqrt5+15\sqrt{5+2\sqrt5}}{6} ≈ 12.34230$ Dihedral angles3–4 cupolaic: $\arccos\left(-\frac{\sqrt3+\sqrt{15}}{6}\right) ≈ 159.09484^\circ$ 4–5: $\arccos\left(-\sqrt{\frac{5+\sqrt5}{10}}\right) ≈ 148.28253^\circ$ 4–4 prismatic: 144°
3–4 join: $\arccos\left(-\sqrt{\frac{10-2\sqrt5}{15}}\right) ≈ 127.37737^\circ$ 4–4 join: $\arccos\left(-\sqrt{\frac{5-\sqrt5}{10}}\right) ≈ 121.71747^\circ$ Central density1
Number of external pieces32
Level of complexity12
Related polytopes
ArmyEpobcu
RegimentEpobcu
DualOrthodeltodeltoidal triacontahedron
Abstract & topological properties
Flag count240
Euler characteristic2
SurfaceSphere
OrientableYes
Genus0
Properties
SymmetryH2×A1, order 20
ConvexYes
NatureTame

The elongated pentagonal orthobicupola is one of the 92 Johnson solids (J38). It consists of 10 triangles, 5+5+10 squares, and 2 pentagons. It can be constructed by inserting a decagonal prism between the two halves of the pentagonal orthobicupola.

## Vertex coordinates

An elongated pentagonal orthobicupola of edge length 1 has the following vertices:

• $\left(±\frac12,\,±\frac{\sqrt{5+2\sqrt5}}{2},\,±\frac12\right),$ • $\left(±\frac{3+\sqrt5}{4},\,±\sqrt{\frac{5+\sqrt5}{8}},\,±\frac12\right),$ • $\left(±\frac{1+\sqrt5}{2},\,0,\,±\frac12\right),$ • $\left(±\frac12,\,-\sqrt{\frac{5+2\sqrt5}{20}},\,±\frac{1+2\sqrt{\frac{5-\sqrt5}{10}}}{2}\right),$ • $\left(±\frac{1+\sqrt5}{4},\,\sqrt{\frac{5-\sqrt5}{40}},\,±\frac{1+2\sqrt{\frac{5-\sqrt5}{10}}}{2}\right),$ • $\left(0,\,\sqrt{\frac{5+\sqrt5}{10}},\,±\frac{1+2\sqrt{\frac{5-\sqrt5}{10}}}{2}\right),$ 