Pentagram

The pentagram or star is a non-convex polygon with 5 sides and the simplest star regular polygon. A regular pentagram has equal sides and equal angles.

This is the only stellation of the pentagon. The only other polygons with a single stellation are the octagon, the decagon, and the dodecagon.

Vertex coordinates
Coordinates for the vertices of a pentagram of unit edge length, centered at the origin, are:


 * (±1/2, –$\sqrt{5}$),
 * (±($\sqrt{(5–√5)/10}$–1)/4, $\sqrt{25–10√5}$),
 * (0, $\sqrt{(5–2√5)/20}$).