Elongated bipyramid

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Elongated bipyramid
Elongated hexagonal dipyramid.png
Example: elongated hexagonal bipyramid
Faces 2n triangles
n squares
Edges 5n
Vertices 2n + 2
Symmetry group Dnh, [n,2], (*n22)
Rotation group Dn, [n,2]+, (n22)
Dual polyhedron bifrustums
Properties convex

In geometry, the elongated bipyramids are an infinite set of polyhedra, constructed by elongating an n-gonal bipyramid (by inserting an n-gonal prism between its congruent halves).

Contents

There are three elongated bipyramids that are Johnson solids:

Higher forms can be constructed with isosceles triangles.

Forms

Name elongated triangular bipyramid
J14
elongated square bipyramid
J15
elongated pentagonal bipyramid
J16
elongated
hexagonal
bipyramid
TypeEquilateralIrregular
Image Elongated triangular dipyramid.png Elongated square dipyramid.png Elongated pentagonal dipyramid.png Elongated hexagonal dipyramid.png
Faces6 triangles,
3 squares
8 triangles,
4 squares
10 triangles,
5 squares
12 triangles,
6 squares
Dual triangular bifrustum square bifrustum pentagonal bifrustum hexagonal bifrustum

Applications

Elongated bipyramids are sometimes used as dice, especially to make dice with atypical side count, such as 5 or 7. Such a die has numbers written on the square faces, which are usually heightened into rectangles for convenience in rolling. Whichever number comes face-up when the die is rolled is the side that is to be read.

See also

Related Research Articles

In geometry, a Johnson solid, sometimes also known as a Johnson–Zalgaller solid, is a strictly convex polyhedron whose faces are regular polygons. They are sometimes defined to exclude the uniform polyhedrons. There are ninety-two solids with such a property: the first solids are the pyramids, cupolas. and a rotunda; some of the solids may be constructed by attaching with those previous solids, whereas others may not. These solids are named after mathematicians Norman Johnson and Victor Zalgaller.

<span class="mw-page-title-main">Gyroelongated square bipyramid</span> 17th Johnson solid

In geometry, the gyroelongated square bipyramid is a polyhedron with 16 triangular faces. it can be constructed from a square antiprism by attaching two equilateral square pyramids to each of its square faces. The same shape is also called hexakaidecadeltahedron, heccaidecadeltahedron, or tetrakis square antiprism; these last names mean a polyhedron with 16 triangular faces. It is an example of deltahedron, and of a Johnson solid.

<span class="mw-page-title-main">Gyroelongated square pyramid</span> 10th Johnson solid (13 faces)

In geometry, the gyroelongated square pyramid is the Johnson solid that can be constructed by attaching an equilateral square pyramid to a square antiprism. It occurs in chemistry; for example, the square antiprismatic molecular geometry.

<span class="mw-page-title-main">Square cupola</span> Cupola with octagonal base

In geometry, the square cupola the cupola with octagonal base. In the case of edges are equal in length, it is the Johnson solid, a convex polyhedron with faces are regular. It can be used to construct many polyhedrons, particularly in other Johnson solids.

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

In geometry, the elongated square cupola is a polyhedron constructed from an octagonal prism by attaching square cupola onto its base. It is an example of Johnson solid.

<span class="mw-page-title-main">Square orthobicupola</span> 28th Johnson solid; 2 square cupolae joined base-to-base

In geometry, the square orthobicupola is one of the Johnson solids. As the name suggests, it can be constructed by joining two square cupolae along their octagonal bases, matching like faces. A 45-degree rotation of one cupola before the joining yields a square gyrobicupola.

<span class="mw-page-title-main">Elongated square pyramid</span> Polyhedron with cube and square pyramid

In geometry, the elongated square pyramid is a convex polyhedron constructed from a cube by attaching an equilateral square pyramid onto one of its faces. It is an example of Johnson solid. It is topologically self-dual.

<span class="mw-page-title-main">Elongated square bipyramid</span> Cube capped by two square pyramids

In geometry, the elongated square bipyramid is the polyhedron constructed by attaching two equilateral square pyramids onto a cube's faces that are opposite each other. It can also be seen as 4 lunes linked together with squares to squares and triangles to triangles. It is also been named the pencil cube or 12-faced pencil cube due to its shape.

<span class="mw-page-title-main">Elongated pentagonal bipyramid</span> 16th Johnson solid; pentagonal prism capped by pyramids

In geometry, the elongated pentagonal bipyramid is a polyhedron constructed by attaching two pentagonal pyramids onto the base of a pentagonal prism. It is an example of Johnson solid.

<span class="mw-page-title-main">Triangular prism</span> Prism with a 3-sided base

In geometry, a triangular prism or trigonal prism is a prism with 2 triangular bases. If the edges pair with each triangle's vertex and if they are perpendicular to the base, it is a right triangular prism. A right triangular prism may be both semiregular and uniform.

<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 near-miss Johnson solid is a strictly convex polyhedron whose faces are close to being regular polygons but some or all of which are not precisely regular. Thus, it fails to meet the definition of a Johnson solid, a polyhedron whose faces are all regular, though it "can often be physically constructed without noticing the discrepancy" between its regular and irregular faces. The precise number of near-misses depends on how closely the faces of such a polyhedron are required to approximate regular polygons.

<span class="mw-page-title-main">Gyroelongated bipyramid</span> Polyhedron formed by capping an antiprism with pyramids

In geometry, the gyroelongated bipyramids are an infinite set of polyhedra, constructed by elongating an n-gonal bipyramid by inserting an n-gonal antiprism between its congruent halves.

<span class="mw-page-title-main">Elongated pyramid</span> Polyhedron formed by capping a prism with a pyramid

In geometry, the elongated pyramids are an infinite set of polyhedra, constructed by adjoining an n-gonal pyramid to an n-gonal prism. Along with the set of pyramids, these figures are topologically self-dual.

<span class="mw-page-title-main">Gyroelongated pyramid</span> Polyhedron formed by capping an antiprism with a pyramid

In geometry, the gyroelongated pyramids are an infinite set of polyhedra, constructed by adjoining an n-gonal pyramid to an n-gonal antiprism.

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

In geometry, the elongated cupolae are an infinite set of polyhedra, constructed by adjoining an n-gonal cupola to an 2n-gonal prism.

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

In geometry, the gyroelongated cupolae are an infinite set of polyhedra, constructed by adjoining an n-gonal cupola to an 2n-gonal antiprism.

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

In geometry, the gyroelongated bicupolae are an infinite sets of polyhedra, constructed by adjoining two n-gonal cupolas to an n-gonal Antiprism. The triangular, square, and pentagonal gyroelongated bicupola are three of five Johnson solids which are chiral, meaning that they have a "left-handed" and a "right-handed" form.

<span class="mw-page-title-main">Elongated bicupola</span>

In geometry, the elongated bicupolae are two infinite sets of polyhedra, constructed by adjoining two n-gonal cupolas to an n-gonal prism. They have 2n triangles, 4n squares, and 2 n-gon. The ortho forms have the cupola aligned, while gyro forms are counter aligned.

<span class="mw-page-title-main">Diminished trapezohedron</span> Polyhedron made by truncating one end of a trapezohedron

In geometry, a diminished trapezohedron is a polyhedron in an infinite set of polyhedra, constructed by removing one of the polar vertices of a trapezohedron and replacing it by a new face (diminishment). It has one regular n-gonal base face, n triangle faces around the base, and n kites meeting on top. The kites can also be replaced by rhombi with specific proportions.

References