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. 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).
Dual
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 ( 5 8 + 1 8 5 ) ≈ 25.242 832 961 52 ∘ {\displaystyle \arccos({\frac {5}{8}}+{\frac {1}{8}}{\sqrt {5}})\approx 25.242\,832\,961\,52^{\circ }} , one of arccos ( − 1 8 + 9 40 5 ) ≈ 67.783 011 547 44 ∘ {\displaystyle \arccos(-{\frac {1}{8}}+{\frac {9}{40}}{\sqrt {5}})\approx 67.783\,011\,547\,44^{\circ }} and one of 360 ∘ − arccos ( − 1 4 − 1 10 5 ) ≈ 241.731 322 529 52 ∘ {\displaystyle 360^{\circ }-\arccos(-{\frac {1}{4}}-{\frac {1}{10}}{\sqrt {5}})\approx 241.731\,322\,529\,52^{\circ }} . Its dihedral angles equal arccos ( − 19 − 8 5 41 ) ≈ 154.121 363 125 78 ∘ {\displaystyle \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 7 + 5 6 ≈ 1.539 344 662 92 {\displaystyle {\frac {7+{\sqrt {5}}}{6}}\approx 1.539\,344\,662\,92} .
References
Coxeter, H. S. M. (May 13, 1954). "Uniform Polyhedra". Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences. 246 (916): 401–450. Bibcode:1954RSPTA.246..401C. doi:10.1098/rsta.1954.0003. Wenninger, Magnus (1974). Polyhedron Models. Cambridge University Press. ISBN 0-521-09859-9. OCLC 1738087. Wenninger, Magnus (1983), Dual Models, Cambridge University Press, ISBN 978-0-521-54325-5, MR 0730208
External links Weisstein, Eric W. "Uniform Polyhedron". MathWorld. Weisstein, Eric W. "Small dodecicosidodecahedron". MathWorld. Weisstein, Eric W. "Small dodecacronic hexecontahedron". MathWorld.






