Hendecagram

The hendecagram, or henge, is a polygon with 11 sides. It's created by taking the second stellation of a hendecagon. A regular hendecagram has equal sides and equal angles.

It is one of four stellations of the hendecagon, the other three being the small hendecagram, the great hendecagram, and the grand hendecagram. The name "hendecagram" is often used to describe any of these shapes.

Vertex coordinates
Coordinates for a heptagon of edge length 2sin(3π/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)).