Pentagrammic-enneagonal duoprism

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Pentagrammic-enneagonal duoprism
Rank4
TypeUniform
Notation
Bowers style acronymStarendip
Coxeter diagramx5/2o x9o ()
Elements
Cells9 pentagrammic prisms, 5 enneagonal prisms
Faces45 squares, 9 pentagrams, 5 enneagons
Edges45+45
Vertices45
Vertex figureDigonal disphenoid, edge lengths (5–1)/2 (base 1), 2cos(π/9) (base 2), 2 (sides)
Measures (edge length 1)
Circumradius
Hypervolume
Dichoral anglesStip–5/2–stip: 140°
 Stip–4–ep: 90°
 Ep–9–ep: 36°
Central density2
Number of external pieces19
Level of complexity12
Related polytopes
ArmySemi-uniform peendip
RegimentStarendip
DualPentagrammic-enneagonal duotegum
ConjugatesPentagonal-enneagonal duoprism, Pentagonal-enneagrammic duoprism, Pentagonal-great enneagrammic duoprism, Pentagrammic-enneagrammic duoprism, Pentagrammic-great enneagrammic duoprism
Abstract & topological properties
Euler characteristic0
OrientableYes
Properties
SymmetryH2×I2(9), order 180
ConvexNo
NatureTame

The pentagrammic-enneagonal duoprism, also known as starendip or the 5/2-9 duoprism, is a uniform duoprism that consists of 9 pentagrammic prisms and 5 enneagonal prisms, with 2 of each at each vertex.

Vertex coordinates[edit | edit source]

The coordinates of a pentagrammic-enneagonal duoprism, centered at the origin and with edge length 2sin(π/9), are given by:

where j = 2, 4, 8.

External links[edit | edit source]