Tridecagram

Tridecagram
(OFF file)
Rank	2
Type	Regular
Space	Spherical
Notation
Bowers style acronym	Trad
Coxeter diagram	x13/3o
Schläfli symbol	{13/3}
Elements
Edges	13
Vertices	13
Vertex figure	Dyad, length 2cos(3π/13)
Measures (edge length 1)
Circumradius	$\frac{1}{2\sin\frac{3\pi}{13}} ≈ 0.75401$
Inradius	$\frac{1}{2\tan\frac{3\pi}{13}} ≈ 0.56438$
Area	$\frac{13}{4\tan\frac{3\pi}{13}} ≈ 3.66849$
Angle	$\frac{7\pi}{13} ≈ 96.92308^\circ$
Central density	3
Number of external pieces	26
Level of complexity	2
Related polytopes
Army	Tad, edge length $\frac{\sin\frac{\pi}{13}}{\sin\frac{3\pi}{13}}$
Dual	Tridecagram
Conjugates	Tridecagon, Small tridecagram, Medial tridecagram, Great tridecagram, Grand tridecagram
Convex core	Tridecagon
Abstract & topological properties
Flag count	26
Euler characteristic	0
Orientable	Yes
Properties
Symmetry	I2(13), order 26
Convex	No
Nature	Tame

The tridecagram is a non-convex polygon with 13 sides. It's created by taking the second stellation of a tridecagon. A regular tridecagram has equal sides and equal angles.

It is one of five regular 13-sided star polygons, the other four being the small tridecagram, the medial tridecagram, the great tridecagram, and the grand tridecagram.

External links

• Bowers, Jonathan. "Regular Polygons and Other Two Dimensional Shapes".

• Wikipedia Contributors. "Tridecagram".