Hendecagon

{{Infobox polytope The hendecagon, or heng, is a polygon with 11 sides. A regular hendecagon has equal sides and equal angles.
 * image = Regular hendecagon.svg
 * off = Hendecagon.off
 * dim = 2
 * type=Regular
 * obsa = Heng
 * edges = 11
 * vertices = 11
 * verf = Dyad, length 2cos(π/11)
 * schlafli = {11}
 * coxeter = x11o
 * army=Heng
 * symmetry = I2(11), order 22
 * circum = $$\frac{1}{2\sin\left(\frac{\pi}{11}\right)}≈ 1.77473$$
 * inrad = $$\frac{1}{2\tan\left(\frac{\pi}{11}\right)} ≈ 1.70284$$
 * area = $$\frac{11}{4\tan\left(\frac{\pi1{11}\right)} ≈ 9.36564$$
 * angle = $$\frac{9\pi}{11} ≈ 147.27273°$$
 * dual=Hendecagon
 * conjugate=Small hendecagram, hendecagram, great hendecagram, grand hendecagram
 * conv=Yes
 * orient=Yes
 * nat=Tame}}

The combining prefix is hen-, as in hentet, or han-, as in handip.

It has four stellations, these being the small hendecagram, the hendecagram, the great hendecagram, and the grand hendecagram.

Naming
The name hendecagon is derived from the Ancient Greek ἕνδεκα (11) and γωνία (angle), referring to the number of vertices.

Other names include:


 * heng, Bowers style acronym, short for "hendecagon"

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