Elongated triangular bipyramid
|Elongated triangular bipyramid|
J13 - J14 - J15
|Symmetry group||D3h, [3,2], (*322)|
|Rotation group||D3, [3,2]+, (322)|
|Dual polyhedron||Triangular bifrustum|
In geometry, the elongated triangular bipyramid (or dipyramid) is one of the Johnson solids (J14), convex polyhedra whose faces are regular polygons. As the name suggests, it can be constructed by elongating a triangular bipyramid (J12) by inserting a triangular prism between its congruent halves.
A Johnson solid is one of 92 strictly convex polyhedra that have regular faces but are not uniform (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.
The nirrosula, an African musical instrument woven out of strips of plant leaves, is made in the form of a series of elongated bipyramids with non-equilateral triangles as the faces of their end caps.
The dual of the elongated triangular bipyramid is called a triangular bifrustum and has 8 faces: 6 trapezoidal and 2 triangular.
|Dual elongated triangular bipyramid||Net of dual|
- 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.
- Gerdes, Paulus (2009), "Exploration of technologies, emerging from African cultural practices, in mathematics (teacher) education", ZDM, the International Journal on Mathematics Education 42 (1): 11–17, doi:10.1007/s11858-009-0208-2.
- Stephen Wolfram, "Elongated triangular dipyramid" from Wolfram Alpha. Retrieved July 22, 2010.
- Weisstein, Eric W., "Johnson solid", MathWorld.
- Weisstein, Eric W., "Elongated triangular bipyramid", MathWorld.
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