Tridecagon facts for kids

Quick facts for kids Regular tridecagon
A regular tridecagon
Type	Regular polygon
Edges and vertices	13
Schläfli symbol	{13}
Coxeter diagram
Symmetry group	Dihedral (D₁₃), order 2×13
Internal angle (degrees)	≈152.308°
Dual polygon	Self
Properties	Convex, cyclic, equilateral, isogonal, isotoxal

A tridecagon or trikaidecagon or triskaidecagon or trisdecagon or 13-gon is a shape with 13 sides and 13 corners.

Regular tridecagon

All sides of a regular tridecagon are the same length. Each corner is 147.27°. All corners added together equal 6840°.

The amount of space a regular tridecagon takes up is

A = \frac{13}{4}a^2 \cot \frac{\pi}{13} \simeq 13.1858\,a^2.

a is the length of one of its sides.

The regular tridecagon is used as the shape of the Czech 20 korun coin.

An Approximate Tridecagon Construction.
Tridecagon, approximate construction as an animation (3 min 30 s)
Symmetries of a regular tridecagon. Vertices are colored by their symmetry positions. Blue mirrors are drawn through vertices and edge. Gyration orders are given in the center.