In geometry, the elongated pyramids are an infinite set of polyhedra, constructed by adjoining an pyramid to an prism. Along with the set of pyramids, these figures are topologically self-dual.
There are three elongated pyramids that are Johnson solids: Elongated triangular pyramid (), Elongated square pyramid (), and Elongated pentagonal pyramid (). Higher forms can be constructed with isosceles triangles.
Forms name faces elongated triangular pyramid (J7) 3+1 triangles, 3 squares elongated square pyramid (J8) 4 triangles, 4+1 squares elongated pentagonal pyramid (J9) 5 triangles, 5 squares, 1 pentagon
See also Gyroelongated bipyramid Elongated bipyramid Gyroelongated pyramid Diminished trapezohedron
References Norman W. Johnson, "Convex Solids with Regular Faces", Canadian Journal of Mathematics, 18, 1966, pages 169–200. Contains the original enumeration of the 92 solids and the conjecture that there are no others. The first proof that there are only 92 Johnson solids.