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Tridecagon facts for kids

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Regular tridecagon
Triskaidecagon.svg
A regular tridecagon
Type Regular polygon
Edges and vertices 13
Schläfli symbol {13}
Coxeter diagram CDel node 1.pngCDel 13.pngCDel node.png
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°.

Area

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.

Numismatic use

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

20 CZK.png

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