Grand hendecagram

The grand hendecagram, or gahn, is a non-convex polygon with 11 sides. It's created by taking the fourth stellation of a hendecagon. A regular grand hendecagram has equal sides and equal angles.

It is one of four regular 11-sided star polygons, the other three being the small hendecagram, the hendecagram, and the great hendecagram.

Vertex coordinates
Coordinates for a grand hendecagram of edge length 2sin(5π/11), centered at the origin, are:


 * (1, 0),
 * (cos(2π/11), ±sin(2π/11)),
 * (cos(4π/11), ±sin(4π/11)),
 * (cos(6π/11), ±sin(6π/11)),
 * (cos(8π/11), ±sin(8π/11)),
 * (cos(10π/11), ±sin(10π/11)).