Enneagonal-enneagrammic duoprism

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Enneagonal-enneagrammic duoprism
Rank4
TypeUniform
Notation
Bowers style acronymEstedip
Coxeter diagramx9o x9/2o ()
Elements
Cells9 enneagonal prisms, 9 enneagrammic prisms
Faces81 squares, 9 enneagons, 9 enneagrams
Edges81+81
Vertices81
Vertex figureDigonal disphenoid, edge lengths 2cos(π/9) (base 1), 2cos(2π/9) (base 2), 2 (sides)
Measures (edge length 1)
Circumradius
Hypervolume
Dichoral anglesStep–9/2–step: 140°
 Ep–9–ep: 100°
 Ep–4–step: 90°
Central density2
Number of external pieces27
Level of complexity12
Related polytopes
ArmySemi-uniform edip
RegimentEstedip
DualEnneagonal-ennneagrammic duotegum
ConjugatesEnneagonal-great enneagrammic duoprism, Enneagrammic-great enneagrammic duoprism
Abstract & topological properties
Euler characteristic0
OrientableYes
Properties
SymmetryI2(9)×I2(9), order 324
ConvexNo
NatureTame

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

The name can also refer to the enneagonal-great enneagrammic duoprism.

Vertex coordinates[edit | edit source]

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

where j, k = 2, 4, 8.

External links[edit | edit source]