Triakis octahedron

Tetrakis hexahedron

Deltoidal icositetrahedron

Pentagonal icositetrahedron

In geometry, an icositetrahedron[1] refers to a polyhedron with 24 faces, none of which are regular polyhedra. However, many are composed of regular polygons, such as the triaugmented dodecahedron and the disphenocingulum. Some icositetrahedra are near-spherical, but are not composed of regular polygons. A minimum of 14 vertices is required to form a icositetahedron.[2]

Symmetry

There are many symmetric forms, and the ones with highest symmetry have chiral icosahedral symmetry:

Four Catalan solids, convex:

27 uniform star-polyhedral duals: (self-intersecting)

Examples with lower symmetry include certain dual polyhedra of Johnson solids , such as the gyroelongated square bicupola and the elongated square gyrobicupola.

Common examples

Common examples include prisms and pyramids, and include certain Johnson solids and Catalan solids.

Icositrigonal pyramids

Icositrigonal pyramids are a type of cone with an icositrigon as a base, with 24 faces, 46 edges, and 24 vertices.[3] Regular icositrigonal pyramids have a regular icositrigon as a base, and its Schläfli symbol is {}∨{23}. The surface area and volume with side length and height can be calculated as follows:[3]

Icosidigonal prism

Icosidigonal prisms are a type of cylinder with an icosidigon as a base, with 24 faces, 66 edges, and 44 vertices.[4] Regular icosidigonal prisms have a regular icosidigon as a base, with each face a rectangle. Every vertex borders 2 squares and an icosidigon base. Its vertex configuration is , its Schläfli symbol is {22}×{} or t{2,22}, its Coxeter diagram is , and its Conway polyhedron notation is P22. The surface area and volume with side length and height can be calculated as follows:

Hendecagonal antiprism

A hendecagonal antiprism

Hendecagonal antiprisms are antiprisms with a hendecagon as a base, with 24 faces, 44 edges, and 22 vertices. Regular hendecagonal antiprisms have a regular hendecagon as a base, with each face an equilateral triangle. Every vertex borders 2 triangles and a hendecagon base. Its vertex configuration is .

Dodecagonal trapezohedron

Dodecagonal trapezohedra are the tenth member of the trapezohedra family, made of 24 congruent kites arranged radially. Every dodecagonal trapezohedron has 24 faces, 28 edges, and 26 vertices. There are two types of vertices, ones bordering 12 kits and ones bordering 3. Its dual polyhedron is the Hendecagonal antiprism.[5] Its Schläfli symbol is { }⨁{12}, its Coxeter diagram is or , and its Conway polyhedron notation is dA12.

Dodecagonal trapezohedra are isohedral figures.

Johnson solids

There are two examples of Johnson solids which are icositetrahedra. They are listed as follows:

Name Image Designation Vertices Edges Faces Types of faces Symmetry group Net
Disphenocingulum J90 16 38 24 20 equilateral triangle,

4 squares

D2d
Triaugmented dodecahedron J61 23 45 24 15 equilateral triangles,

9 pentagons

C3v

Catalan Solids

There are 5 types of icositetrahedra with different topologies.[6] The pentagonal icositetetrahedron has two mirror images (enantiomorphs), so geometrically there are 4 distinct Catalan icositetetrahedra.

Name Image Net Dual Faces Edges Vertices Face Configuration Point Group
Triakis octahedron Triakis octahedron

(animation)

Truncated cube 24 36 14 Isosceles triangle

V3.8.8

Oh
Tetrakis hexahedron Tetrakis hexahedron

(animation)

Truncated octahedron 24 36 14 Isosceles triangle

V4.6.6

Oh
Deltoidal icositetrahedron Deltoidal icositetrahedron

(animation)

Rhombicuboctahedron 24 48 26 Kite

V3.4.4.4

Oh
Pentagonal icositetrahedron Pentagonal icositetrahedron (Ccw)

(animation) Pentagonal icositetrahedron (Cw) (animation)

Snub cube 24 60 38 irregular pentagon

V3.3.3.3.4

O

Uniform star polyhedra

Some uniform star polyhedra also have 24 faces:

Name Image Wythoff symbol Vertex figure Symmetry group Faces Edges Vertices Euler characteristic Density Faces by sides
Ditrigonal dodecadodecahedron 3 | 5/3 5

(5.5/3)3

Ih 24 60 20 -16 4 12{5}+12{5/2}
Dodecadodecahedron 5 5/2

5.5/2.5.5/2

Ih 24 60 20 -16 4 12{5}+12{5/2}
Truncated great dodecahedron 2 5/2 | 5

10.10.5/2

Ih 24 90 60 -6 3 12{5/2}+12{10}
Small stellated truncated dodecahedron 2 5 | 5/3

10/3.10/3.5

Ih 24 90 60 -6 9 12{5}+12{10/3}

Types of icositetrahedra

Name Type Image Identifier Faces Edges Vertices Euler characteristic Types of faces Symmetry Net
Icosidigonal prism Prism t{2,22}

{22}x{}

24 66 44 2 2 icosidigons,

22 squares

D22h, [22,2], (*22 2 2), order 88
Icositrigonal pyramid Pyramid ( )∨{23} 24 46 24 2 1 icositrigon,

23 triangles

C23v, [23], (*23 23)
Icosidigonal frustum Frustum 24 66 44 2 2 icosidigons,

22 trapezoids

D22h, [22,2], (*22 2 2), order 88
Dodecagonal bipyramid Bipyramid { } + {12}

24 36 14 2 12 triangles D12h, [12,2], (*2 2 12), order 48
Dodecagonal trapezohedron Trapezohedron { }⨁{12}[7] 24 48 26 2 24 kites D12d, [2+,12], (2*12)
Hendecagonal antiprism Antiprism s{2,22}

sr{2,11}

24 44 22 2 2 hendecagons,

22 triangles

D11d, [2+,22], (2*11), order 44
Hendecagonal cupola Cupola 24 55 33 2 11 equilateral triangles,

11 squares, 1 regular hendecagon, 1 regular icosidigon

D11d, [2+,22], (2*11), order 44
Deltoidal icositetrahedron Johnson solid 24 48 26 2 24 kites D4d

See Also

References

  1. ^ "Greek numerical prefixes". www.georgehart.com. Retrieved 2025-02-02.
  2. ^ "Enumeration of Polyhedra - Numericana". www.numericana.com. Retrieved 2025-02-02.
  3. ^ a b "Icositrigonal pyramid - Wolfram|Alpha". www.wolframalpha.com. Archived from the original on 2024-11-30. Retrieved 2025-02-02.
  4. ^ "Icosidigonal prism". Wolfram Alpha. Retrieved 2025-02-02.
  5. ^ "12-trapezohedron". Wolfram Alpha. Retrieved 2025-02-02.
  6. ^ "Sur la théorie des quantités positives et négatives", Cours d'analyse de l'École Royale Polytechnique, Cambridge University Press, pp. 403–437, 2009-07-20, retrieved 2025-02-02
  7. ^ Johnson, N.W. (2018). "Chapter 11: Finite symmetry groups". Geometries and Transformations. p. 235. ISBN 978-1-107-10340-5.


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