Small dodecicosidodecahedron

{{Short description|Polyhedron with 44 faces}}

{{Uniform polyhedra db|Uniform polyhedron stat table|lDID}}

File:Small dodecicosidodecahedron.stl

In geometry, the small dodecicosidodecahedron (or small dodekicosidodecahedron) is a nonconvex uniform polyhedron, indexed as U33. It has 44 faces (20 triangles, 12 pentagons, and 12 decagons), 120 edges, and 60 vertices.{{Cite web|url=https://www.mathconsult.ch/static/unipoly/33.html|title=33: small dodecicosidodecahedron|last=Maeder|first=Roman|date=|website=MathConsult|archive-url=|archive-date=|access-date=}} Its vertex figure is a crossed quadrilateral.

Related polyhedra

It shares its vertex arrangement with the small stellated truncated dodecahedron and the uniform compounds of 6 or 12 pentagrammic prisms. It additionally shares its edge arrangement with the rhombicosidodecahedron (having the triangular and pentagonal faces in common), and with the small rhombidodecahedron (having the decagonal faces in common).

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Rhombicosidodecahedron

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Small dodecicosidodecahedron

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Small rhombidodecahedron

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Small stellated truncated dodecahedron

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Compound of six pentagrammic prisms

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Compound of twelve pentagrammic prisms

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=Dual=

{{Uniform polyhedra db|Uniform dual polyhedron stat table|lDID}}

File:Small dodecacronic hexecontahedron.stl

The dual polyhedron to the small dodecicosidodecahedron is the small dodecacronic hexecontahedron (or small sagittal ditriacontahedron). It is visually identical to the small rhombidodecacron. Its faces are darts. A part of each dart lies inside the solid, hence is invisible in solid models.

== Proportions ==

Faces have two angles of \arccos(\frac{5}{8}+\frac{1}{8}\sqrt{5})\approx 25.242\,832\,961\,52^{\circ}, one of \arccos(-\frac{1}{8}+\frac{9}{40}\sqrt{5})\approx 67.783\,011\,547\,44^{\circ} and one of 360^{\circ}-\arccos(-\frac{1}{4}-\frac{1}{10}\sqrt{5})\approx 241.731\,322\,529\,52^{\circ}. Its dihedral angles equal \arccos({\frac{-19-8\sqrt{5}}{41}})\approx 154.121\,363\,125\,78^{\circ}. The ratio between the lengths of the long and short edges is \frac{7+\sqrt{5}}{6}\approx 1.539\,344\,662\,92.

References

{{Reflist}}

  • {{cite journal| last = Coxeter| first = H. S. M.| authorlink = Harold Scott MacDonald Coxeter| title = Uniform Polyhedra| journal = Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences| volume = 246| issue = 916| date = May 13, 1954| pages = 401–450| doi = 10.1098/rsta.1954.0003| bibcode = 1954RSPTA.246..401C}}
  • {{cite book | first=Magnus | last=Wenninger | authorlink=Magnus Wenninger | title=Polyhedron Models | publisher=Cambridge University Press | year=1974 | isbn=0-521-09859-9 | oclc=1738087 }}
  • {{Citation | last1=Wenninger | first1=Magnus | author1-link=Magnus Wenninger | title=Dual Models | publisher=Cambridge University Press | isbn=978-0-521-54325-5 |mr=730208 | year=1983}}