# Tridecagram

Tridecagram Rank2
TypeRegular
SpaceSpherical
Notation
Coxeter diagramx13/3o
Schläfli symbol{13/3}
Elements
Edges13
Vertices13
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 density3
Number of external pieces26
Level of complexity2
Related polytopes
ArmyTad, edge length $\frac{\sin\frac{\pi}{13}}{\sin\frac{3\pi}{13}}$ DualTridecagram
ConjugatesTridecagon, Small tridecagram, Medial tridecagram, Great tridecagram, Grand tridecagram
Convex coreTridecagon
Abstract & topological properties
Flag count26
Euler characteristic0
OrientableYes
Properties
SymmetryI2(13), order 26
ConvexNo
NatureTame

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.