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Enneadecagon facts for kids

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Quick facts for kids
Regular enneadecagon
Enneadecagon.svg
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.


Images for kids

  • 01-Neunzehneck-Animation

    Enneadecagon, approximate construction as an animation, with 15 s pause

  • Symmetries of enneadecagon

    Symmetries of a regular enneadecagon. Vertices are colored by their symmetry positions. Blue mirror lines are drawn through vertices and edges. Gyration orders are given in the center.

See also

Kids robot.svg In Spanish: Eneadecágono para niños

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Enneadecagon Facts for Kids. Kiddle Encyclopedia.