Stellated decagram

The stellated decagram or sadag is a polygon compound composed of two pentagrams. As such it has 10 edges and 10 vertices.

It is the third stellation of the decagon.

Its quotient prismatic equivalent is the pentagrammic retroprism, which is three-dimensional.

Vertex coordinates
Coordinates for the vertices of a stellated decagram of edge length 1 centered at the origin are given by:


 * $$\left(±\frac12,\,±\sqrt{\frac{5-2\sqrt5}{20}}\right),$$
 * $$\left(±\frac{\sqrt5-1}{4},\,±\sqrt{\frac{5+\sqrt5}{40}}\right),$$
 * $$\left(0,\,±\sqrt{\frac{5-\sqrt5}{10}}\right).$$