Triangular orthobicupola

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Triangular orthobicupola
Triangular orthobicupola.png
Type Johnson
J26J27J28
Faces 2+6 triangles
6 squares
Edges 24
Vertices 12
Vertex configuration 6(32.42)
6(3.4.3.4)
Symmetry group D3h
Dual polyhedron Trapezo-rhombic dodecahedron
Properties convex
Net
Johnson solid 27 net.png

In geometry, the triangular orthobicupola is one of the Johnson solids (J27). As the name suggests, it can be constructed by attaching two triangular cupolas (J3) along their bases. It has an equal number of squares and triangles at each vertex; however, it is not vertex-transitive. It is also called an anticuboctahedron, twisted cuboctahedron or disheptahedron. It is also a canonical polyhedron.

Contents

A Johnson solid is one of 92 strictly convex polyhedra that is composed of regular polygon faces but are not uniform polyhedra (that is, they are not Platonic solids , Archimedean solids , prisms , or antiprisms ). They were named by Norman Johnson , who first listed these polyhedra in 1966. [1]

The triangular orthobicupola is the first in an infinite set of orthobicupolae.

Relation to cuboctahedra

Triangular orthobicupolaTriangular gyrobicupola
Triangular orthobicupola wireframe.png Cuboctahedron 3 planes.png
Both the triangular orthobicupola and the cuboctahedron (triangular gyrobicupola) contain a central regular hexagon. They can be dissected on this hexagon into pairs of triangular cupolae.

The triangular orthobicupola has a superficial resemblance to the cuboctahedron, which would be known as the triangular gyrobicupola in the nomenclature of Johnson solids the difference is that the two triangular cupolas which make up the triangular orthobicupola are joined so that pairs of matching sides abut (hence, "ortho"); the cuboctahedron is joined so that triangles abut squares and vice versa. Given a triangular orthobicupola, a 60-degree rotation of one cupola before the joining yields a cuboctahedron. Hence, another name for the triangular orthobicupola is the anticuboctahedron.

The elongated triangular orthobicupola (J35), which is constructed by elongating this solid, has a (different) special relationship with the rhombicuboctahedron.

The dual of the triangular orthobicupola is the trapezo-rhombic dodecahedron. It has 6 rhombic and 6 trapezoidal faces, and is similar to the rhombic dodecahedron.

Formulae

The following formulae for volume, surface area, and circumradius can be used if all faces are regular, with edge length a: [2]

The circumradius of a triangular orthobicupola is the same as the edge length (C = a).

The rectified cubic honeycomb can be dissected and rebuilt as a space-filling lattice of triangular orthobicupolae and square pyramids. [3]

Related Research Articles

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<span class="mw-page-title-main">Triangular cupola</span> 3rd Johnson solid (8 faces)

In geometry, the triangular cupola is one of the Johnson solids. It can be seen as half a cuboctahedron.

<span class="mw-page-title-main">Square cupola</span> 4th Johnson solid (10 faces)

In geometry, the square cupola, sometimes called lesser dome, is one of the Johnson solids. It can be obtained as a slice of the rhombicuboctahedron. As in all cupolae, the base polygon has twice as many edges and vertices as the top; in this case the base polygon is an octagon.

<span class="mw-page-title-main">Elongated square cupola</span> 19th Johnson solid

In geometry, the elongated square cupola is one of the Johnson solids. As the name suggests, it can be constructed by elongating a square cupola by attaching an octagonal prism to its base. The solid can be seen as a rhombicuboctahedron with its "lid" removed.

<span class="mw-page-title-main">Square gyrobicupola</span> 29th Johnson solid; 2 square cupolae joined base-to-base

In geometry, the square gyrobicupola is one of the Johnson solids. Like the square orthobicupola, it can be obtained by joining two square cupolae along their bases. The difference is that in this solid, the two halves are rotated 45 degrees with respect to one another.

<span class="mw-page-title-main">Elongated square bipyramid</span> 15th Johnson solid; cube capped by 2 square pyramids

In geometry, the elongated square bipyramid is one of the Johnson solids. As the name suggests, it can be constructed by elongating an octahedron by inserting a cube between its congruent halves.

<span class="mw-page-title-main">Elongated pentagonal cupola</span> 20th Johnson solid

In geometry, the elongated pentagonal cupola is one of the Johnson solids. As the name suggests, it can be constructed by elongating a pentagonal cupola by attaching a decagonal prism to its base. The solid can also be seen as an elongated pentagonal orthobicupola with its "lid" removed.

<span class="mw-page-title-main">Elongated triangular cupola</span> 18th Johnson solid

In geometry, the elongated triangular cupola is one of the Johnson solids. As the name suggests, it can be constructed by elongating a triangular cupola by attaching a hexagonal prism to its base.

<span class="mw-page-title-main">Gyroelongated triangular cupola</span>

In geometry, the gyroelongated triangular cupola is one of the Johnson solids (J22). It can be constructed by attaching a hexagonal antiprism to the base of a triangular cupola (J3). This is called "gyroelongation", which means that an antiprism is joined to the base of a solid, or between the bases of more than one solid.

<span class="mw-page-title-main">Elongated triangular orthobicupola</span> Johnson solid with 20 faces

In geometry, the elongated triangular orthobicupola or cantellated triangular prism is one of the Johnson solids. As the name suggests, it can be constructed by elongating a triangular orthobicupola by inserting a hexagonal prism between its two halves. The resulting solid is superficially similar to the rhombicuboctahedron, with the difference that it has threefold rotational symmetry about its axis instead of fourfold symmetry.

<span class="mw-page-title-main">Elongated triangular gyrobicupola</span> 36th Johnson solid

In geometry, the elongated triangular gyrobicupola is one of the Johnson solids. As the name suggests, it can be constructed by elongating a "triangular gyrobicupola," or cuboctahedron, by inserting a hexagonal prism between its two halves, which are congruent triangular cupolae. Rotating one of the cupolae through 60 degrees before the elongation yields the triangular orthobicupola.

<span class="mw-page-title-main">Gyroelongated triangular bicupola</span> 44th Johnson solid

In geometry, the gyroelongated triangular bicupola is one of the Johnson solids. As the name suggests, it can be constructed by gyroelongating a triangular bicupola by inserting a hexagonal antiprism between its congruent halves.

<span class="mw-page-title-main">Bicupola (geometry)</span> Solid made from 2 cupolae joined base-to-base

In geometry, a bicupola is a solid formed by connecting two cupolae on their bases.

In geometry, a quasiregular polyhedron is a uniform polyhedron that has exactly two kinds of regular faces, which alternate around each vertex. They are vertex-transitive and edge-transitive, hence a step closer to regular polyhedra than the semiregular, which are merely vertex-transitive.

<span class="mw-page-title-main">First stellation of the rhombic dodecahedron</span>

In geometry, the first stellation of the rhombic dodecahedron is a self-intersecting polyhedron with 12 faces, each of which is a non-convex hexagon. It is a stellation of the rhombic dodecahedron and has the same outer shell and the same visual appearance as two other shapes: a solid, Escher's solid, with 48 triangular faces, and a polyhedral compound of three flattened octahedra with 24 overlapping triangular faces.

References

  1. Johnson, Norman W. (1966), "Convex polyhedra with regular faces", Canadian Journal of Mathematics , 18: 169–200, doi:10.4153/cjm-1966-021-8, MR   0185507, Zbl   0132.14603 .
  2. Stephen Wolfram, "Triangular orthobicupola" from Wolfram Alpha. Retrieved July 23, 2010.
  3. "J27 honeycomb".