Decagrammic antiprism

The decagrammic antiprism, or stidap, is a prismatic uniform polyhedron. It consists of 20 triangles and 2 decagrams. Each vertex joins one decagram and three triangles. As the name suggests, it is an antiprism based on a decagram.

Vertex coordinates
A decagrammic antiprism of edge length 1 has vertex coordinates given by:
 * $$\left(±\frac12,\,±\frac{\sqrt{5-2\sqrt5}}2,\,H\right),$$
 * $$\left(±\frac{3-\sqrt5}4,\,±\sqrt{\frac{5-\sqrt5}8},\,H\right),$$
 * $$\left(±\frac{\sqrt5-1}2,\,0,\,H\right),$$
 * $$\left(±\frac{\sqrt{5-2\sqrt5}}2,\,±\frac12,\,-H\right),$$
 * $$\left(±\sqrt{\frac{5-\sqrt5}8},\,±\frac{3-\sqrt5}4,\,-H\right),$$
 * $$\left(0,\,±\frac{\sqrt5-1}2,\,-H\right),$$

where H = $$\sqrt{\frac{-4+2\sqrt5+\sqrt{50-22\sqrt5}}8}$$ is the distance between the antiprism's center and the center of one of its bases.