Enneagonal prism

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Enneagonal prism
Rank3
TypeUniform
Notation
Bowers style acronymEp
Coxeter diagram
Conway notationP9
Elements
Faces9 squares, 2 enneagons
Edges9+18
Vertices18
Vertex figureIsosceles triangle, edge lengths 2, 2, 2cos(π/9)
Measures (edge length 1)
Circumradius
Volume
Dihedral angles4–4: 140°
 4–9: 90°
Height1
Central density1
Number of external pieces11
Level of complexity3
Related polytopes
ArmyEp
RegimentEp
DualEnneagonal tegum
ConjugatesEnneagrammic prism, Great enneagrammic prism
Abstract & topological properties
Flag count108
Euler characteristic2
SurfaceSphere
OrientableYes
Genus0
SkeletonGP(9,1)
Properties
SymmetryI2(9)×A1, order 36
ConvexYes
NatureTame

The enneagonal prism, nonagonal prism, or ep, is a prismatic uniform polyhedron. It consists of 2 enneagons and 9 squares. Each vertex joins one enneagon and two squares. As the name suggests, it is a prism based on an enneagon.

Vertex coordinates[edit | edit source]

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

  • ,
  • ,
  • ,
  • ,
  • .

External links[edit | edit source]