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Tridiminished icosahedron
63rd Johnson solid (8 faces) From Wikipedia, the free encyclopedia
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In geometry, the tridiminished icosahedron is a Johnson solid that is constructed by removing three pentagonal pyramids from a regular icosahedron.
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Construction
The tridiminished icosahedron can be constructed by removing three regular pentagonal pyramid from a regular icosahedron.[1] The aftereffect of such construction leaves five equilateral triangles and three regular pentagons.[2] Since all of its faces are regular polygons and the resulting polyhedron remains convex, the tridiminished icosahedron is a Johnson solid, and it is enumerated as the sixty-third Johnson solid .[3] This construction is similar to other Johnson solids as in gyroelongated pentagonal pyramid and metabidiminished icosahedron.[1]
The tridiminished icosahedron is a non-composite polyhedron: there is no plane that intersects its surface only in edges, so that it cannot be thereby divided into two or more regular or Johnson polyhedra.[4]
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Properties
Summarize
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The surface area of a tridiminished icosahedron is the sum of all polygonal faces' area: five equilateral triangles and three regular pentagons. Its volume can be ascertained by subtracting the volume of a regular icosahedron from the volume of three pentagonal pyramids. Given that is the edge length of a tridiminished icosahedron, they are:[2]
A tridiminished icosahedron has three kinds of dihedral angles. These angles are between two triangles: 138.1°, triangle to pentagon: 100.8°, and two pentagons: 63.4°.[5]
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Related figure
The tridiminished icosahedron is a vertex figure of a 4-polytope, a snub 24-cell.[6]
See also
- Augmented tridiminished icosahedron, a Johnson solid by attaching a tetrahedron from a tridiminished icosahedron
References
External links
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