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Enneadecagon facts for kids

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Regular enneadecagon
A regular enneadecagon
Type Regular polygon
Edges and vertices 19
Schläfli symbol {19}
Coxeter diagram CDel node 1.pngCDel 19.pngCDel node.png
Symmetry group Dihedral (D19), order 2×19
Internal angle (degrees) ≈161.052°
Dual polygon Self
Properties Convex, cyclic, equilateral, isogonal, isotoxal

A enneadecagon or 19-gon is a shape with 19 sides and 19 corners. It is also known as an enneakaidecagon or a nonadecagon.

Regular enneadecagon

All sides of a regular enneadecagon are the same length. Each corner is ≈161.052°. All corners added together equal 6840°.

The radius of the circumcircle of the regular enneadecagon with side length t is R=\frac{t}{2} \csc \frac {180}{19} (angle in degrees). The area, where t is the edge length, is \frac{19}{4}t^2 \cot \frac{\pi}{19} \simeq 28.4652\,t^2.

  • Eric W. Weisstein, Enneadecagon at MathWorld.

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