Decagram

The decagram, or dag, is a star polygon with 10 sides. A regular decagram has equal sides and equal angles.

It is the second stellation of the decagon, and the only one that is not a compound. The only other polygons with a single non-compound stellation are the pentagon, the octagon, and the dodecagon.

Vertex coordinates
Coordinates for a decagram of unit edge length, centered at the origin are all sign changes of:


 * (±1/2, ±$\sqrt{(5–√5)/2}$/2),
 * (±(3–$\sqrt{5}$)/4, ±$\sqrt{5–2√5}$),
 * (±($\sqrt{(5–2√5)}$–1)/2, 0).

Representations
A decagram has the following Coxeter diagrams:


 * x10/3o (full symmetry)
 * x5/3x (H2 symmetry)