Snub dodecadodecahedron
Snub dodecadodecahedron | |
---|---|
![]() | |
Type | Uniform star polyhedron |
Elements | F = 84, E = 150 V = 60 (χ = −6) |
Faces by sides | 60{3}+12{5}+12{5/2} |
Wythoff symbol | | 2 5/2 5 |
Symmetry group | I, [5,3]+, 532 |
Index references | U40, C49, W111 |
Dual polyhedron | Medial pentagonal hexecontahedron |
Vertex figure | ![]() 3.3.5/2.3.5 |
Siddid |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/37/Snub_dodecadodecahedron.stl/220px-Snub_dodecadodecahedron.stl.png)
In geometry, the snub dodecadodecahedron is a nonconvex uniform polyhedron, indexed as U40. It has 84 faces (60 triangles, 12 pentagons, and 12 pentagrams), 150 edges, and 60 vertices.[1] It is given a Schläfli symbol sr{5⁄2,5}, as a snub great dodecahedron.
Cartesian coordinates[]
Cartesian coordinates for the vertices of a snub dodecadodecahedron are all the even permutations of
- (±2α, ±2, ±2β),
- (±(α+β/τ+τ), ±(-ατ+β+1/τ), ±(α/τ+βτ-1)),
- (±(-α/τ+βτ+1), ±(-α+β/τ-τ), ±(ατ+β-1/τ)),
- (±(-α/τ+βτ-1), ±(α-β/τ-τ), ±(ατ+β+1/τ)) and
- (±(α+β/τ-τ), ±(ατ-β+1/τ), ±(α/τ+βτ+1)),
with an even number of plus signs, where
- β = (α2/τ+τ)/(ατ−1/τ),
where τ = (1+√5)/2 is the golden mean and α is the positive real root of τα4−α3+2α2−α−1/τ, or approximately 0.7964421. Taking the odd permutations of the above coordinates with an odd number of plus signs gives another form, the enantiomorph of the other one.
Related polyhedra[]
Medial pentagonal hexecontahedron[]
Medial pentagonal hexecontahedron | |
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![]() | |
Type | Star polyhedron |
Face | ![]() |
Elements | F = 60, E = 150 V = 84 (χ = −6) |
Symmetry group | I, [5,3]+, 532 |
Index references | DU40 |
dual polyhedron | Snub dodecadodecahedron |
![](http://upload.wikimedia.org/wikipedia/commons/thumb/2/27/Medial_pentagonal_hexecontahedron.stl/220px-Medial_pentagonal_hexecontahedron.stl.png)
The medial pentagonal hexecontahedron is a nonconvex isohedral polyhedron. It is the dual of the snub dodecadodecahedron. It has 60 intersecting irregular pentagonal faces.
See also[]
References[]
- ^ Maeder, Roman. "40: snub dodecadodecahedron". MathConsult.
{{cite web}}
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- Wenninger, Magnus (1983), Dual Models, Cambridge University Press, doi:10.1017/CBO9780511569371, ISBN 978-0-521-54325-5, MR 0730208
External links[]
- Weisstein, Eric W. "Medial pentagonal hexecontahedron". MathWorld.
- Weisstein, Eric W. "Snub dodecadodecahedron". MathWorld.
- Uniform polyhedra and duals
- Uniform polyhedra
- Polyhedron stubs