Tridecagram

Tridecagram
(OFF file)
Rank	2
Type	Regular
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	${\frac {1}{2\sin {\frac {3\pi }{13}}}}\approx 0.75401$
Inradius	${\frac {1}{2\tan {\frac {3\pi }{13}}}}\approx 0.56438$
Area	${\frac {13}{4\tan {\frac {3\pi }{13}}}}\approx 3.66849$
Angle	${\frac {7\pi }{13}}\approx 96.92308^{\circ }$
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
Schläfli type	{13}
Orientable	Yes
Properties
Symmetry	I2(13), order 26
Convex	No
Nature	Tame

The tridecagram is a non-convex polygon with 13 sides. It is 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".