# Pentagrammic-heptagrammic duoprism

Pentagrammic-heptagrammic duoprism
Rank4
TypeUniform
SpaceSpherical
Bowers style acronymStashedip
Info
Coxeter diagramx5/2o x7/2o
SymmetryH2×I2(7), order 140
ArmySemi-uniform pheddip
RegimentStashedip
Elements
Vertex figureDigonal disphenoid, edge lengths (5–1)/2 (base 1), 2cos(2π/7) (base 2), 2 (sides)
Cells7 pentagrammic prisms, 5 heptagrammic prisms
Faces35 squares, 7 pentagrams, 5 heptagrams
Edges35+35
Vertices35
Measures (edge length 1)
Circumradius$\sqrt{\frac{5-\sqrt{5}}{10}+\frac{1}{4\sin^2\frac{2\pi}{7}}}≈0.82788$ Hypervolume$\frac{7\sqrt{5(5-2\sqrt{5})}}{16\tan\frac{2\pi}{7}}≈0.56681$ Dichoral anglesStip–5/2–stip: 3π/7 ≈ 77.14286°
Ship–7/2–ship: 36°
Stip–4–ship: 90°
Central density4
Related polytopes
DualPentagrammic-heptagrammic duotegum
ConjugatesPentagonal-heptagonal duoprism, Pentagonal-heptagrammic duoprism, Pentagonal-great heptagrammic duoprism, Pentagrammic-heptagonal duoprism, Pentagrammic-great heptagrammic duoprism
Properties
ConvexNo
OrientableYes
NatureTame

The pentagrammic-heptagrammic duoprism, also known as stashedip or the 5/2-7/2 duoprism, is a uniform duoprism that consists of 7 pentagrammic prisms and 5 heptagrammic prisms, with 2 of each meeting at each vertex.

The name can also refer to the pentagrammic-great heptagrammic duoprism.

## Vertex coordinates

The coordinates of a pentagrammic-heptagrammic duoprism, centered at the origin and with edge length 2sin(2π/7), are given by:

• (±sin(2π/7), –sin(2π/7)(5–25)/5, 1, 0),
• (±sin(2π/7), –sin(2π/7)(5–25)/5, cos(2π/7), ±sin(2π/7)),
• (±sin(2π/7), –sin(2π/7)(5–25)/5, cos(4π/7), ±sin(4π/7)),
• (±sin(2π/7), –sin(2π/7)(5–25)/5, cos(6π/7), ±sin(6π/7)),
• (±sin(2π/7)(5–1)/2, sin(2π/7)(5+5)/10, 1, 0),
• (±sin(2π/7)(5–1)/2, sin(2π/7)(5+5)/10, cos(2π/7), ±sin(2π/7)),
• (±sin(2π/7)(5–1)/2, sin(2π/7)(5+5)/10, cos(4π/7), ±sin(4π/7)),
• (±sin(2π/7)(5–1)/2, sin(2π/7)(5+5)/10, cos(6π/7), ±sin(6π/7)),
• (0, –2sin(2π/7)(5–5)/10, 1, 0),
• (0, –2sin(2π/7)(5–5)/10, cos(2π/7), ±sin(2π/7)),
• (0, –2sin(2π/7)(5–5)/10, cos(4π/7), ±sin(4π/7)),
• (0, –2sin(2π/7)(5–5)/10, cos(6π/7), ±sin(6π/7)).