Elongated triangular cupola

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Elongated triangular cupola
Elongated triangular cupola.png
Type Johnson
J17 - J18 - J19
Faces 1+3 triangles
3.3 squares
1 hexagon
Edges 27
Vertices 15
Vertex configuration 6(42.6)
Symmetry group C3v
Dual polyhedron -
Properties convex
Johnson solid 18 net.png

In geometry, the elongated triangular cupola is one of the Johnson solids (J18). As the name suggests, it can be constructed by elongating a triangular cupola (J3) by attaching a hexagonal prism to its base.

A Johnson solid is one of 92 strictly convex regular-faced polyhedra, but which is not uniform, i.e., not a Platonic solid, Archimedean solid, prism or antiprism. They are named by Norman Johnson who first enumerated the set in 1966.


The following formulae for volume and surface area can be used if all faces are regular, with edge length a:[1]



Dual polyhedron[edit]

The dual of the elongated triangular cupola has 15 faces: 6 isosceles triangles, 3 rhombi, and 6 quadrilaterals.

Dual elongated triangular cupola Net of dual
Dual elongated triangular cupola.png Dual elongated triangular cupola net.png


  1. ^ Stephen Wolfram, "Elongated triangular cupola" from Wolfram Alpha. Retrieved July 22, 2010.

External links[edit]