. "In geometry, the gyroelongated dipyramids or 2n-gonal Deltahedron are an infinite set of polyhedra, constructed by elongating an n-agonal bipyramid by inserting an n-agonal antiprism between its congruent halves."@en . . "In geometry, the gyroelongated dipyramids or 2n-gonal Deltahedron are an infinite set of polyhedra, constructed by elongating an n-agonal bipyramid by inserting an n-agonal antiprism between its congruent halves. Two members of the set can be deltahedra, that is, constructed entirely of equilateral triangles: the gyroelongated square dipyramid, a Johnson solid, and the icosahedron, a Platonic solid. The gyroelongated triangular dipyramid can be made with equilateral triangles, but is not a deltahedron because it has coplanar faces, i.e. is not strictly convex. The other members can be constructed with isosceles triangles."@en . . "Gyroelongated dipyramid"@en . .