# Small hendecagrammic duoprism

Small hendecagrammic duoprism
Rank4
TypeUniform
SpaceSpherical
Notation
Coxeter diagramx11/2o x11/2o (           )
Elements
Cells22 small hendecagrammic prisms
Faces121 squares, 22 small hendecagrams
Edges242
Vertices121
Vertex figureTetragonal disphenoid, edge lengths 2cos(2π/11) (bases) and 2 (sides)
Measures (edge length 1)
Circumradius$\frac{\sqrt2}{2\sin\frac{2\pi}{11}} ≈ 1.30790$ Inradius$\frac{1}{2\tan\frac{2\pi}{11}} ≈ 0.77802$ Hypervolume$\frac{121}{16\tan^2\frac{2\pi}{11}} ≈ 18.31056$ Dichoral anglesSishenp–11/2–sishenp: $\frac{7\pi}{11} ≈ 114.54545°$ Sishenp–4–sishenp: 90°
Central density4
Number of external pieces44
Level of complexity12
Related polytopes
ArmyHandip
DualSmall hendecagrammic duotegum
ConjugatesHendecagonal duoprism, Hendecagrammic duoprism, Great hendecagrammic duoprism, Grand hendecagrammic duoprism
Abstract & topological properties
Euler characteristic0
OrientableYes
Properties
SymmetryI2(11)≀S2, order 968
ConvexNo
NatureTame

The small hendecagrammic duoprism, also known as the small hendecagrammic-small hendecagrammic duoprism, the 11/2 duoprism or the 11/2-11/2 duoprism, is a noble uniform duoprism that consists of 22 small hendecagrammic prisms, with 4 meeting at each vertex.

## Vertex coordinates

The coordinates of a small hendecagrammic duoprism, centered at the origin and with edge length 2sin(2π/11), are given by:

• $\left(1,\,0,\,1,\,0\right),$ • $\left(1,\,0,\,\cos\left(\frac{k\pi}{11}\right),\,±\sin\left(\frac{k\pi}{11}\right)\right),$ • $\left(\cos\left(\frac{j\pi}{11}\right),\,±\sin\left(\frac{j\pi}{11}\right),\,1,\,0\right),$ • $\left(\cos\left(\frac{j\pi}{11}\right),\,±\sin\left(\frac{j\pi}{11}\right),\,\cos\left(\frac{k\pi}{11}\right),\,±\sin\left(\frac{k\pi}{11}\right)\right),$ where j, k = 2, 4, 6, 8, 10.