In geometry, the pentagrammic crossed-antiprism is one in an infinite set of nonconvex antiprisms formed by triangle sides and two regular star polygon caps, in this case two pentagrams. It differs from the pentagrammic antiprism by having triangular lateral faces which intersect (or "cross") the antiprism's axis of symmetry; in other words, for each lateral face, one of the triangle's vertices is on the opposite side of the axis of symmetry from the other two. This polyhedron is identified with the indexed name U80 as a uniform polyhedron.
The pentagrammic crossed-antiprism may be inscribed within an icosahedron, and has ten triangular faces in common with the great icosahedron. It has the same vertex arrangement as the pentagonal antiprism. In fact, it may be considered as a parabidiminished great icosahedron.
See also Prismatic uniform polyhedron
External links Weisstein, Eric W. "Pentagrammic crossed antiprism". MathWorld. http://www.mathconsult.ch/showroom/unipoly/80.html http://bulatov.org/polyhedra/uniform/u05.html https://web.archive.org/web/20050313234519/http://www.math.technion.ac.il/~rl/kaleido/data/05.html






