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Nonagon facts for kids

Kids Encyclopedia Facts
Enneagon
A nonagon

A nonagon or 9-gon is a shape with 9 sides and 9 corners.

Regular nonagon

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

Area

The amount of space a regular nonagon takes up is

A = \frac{9}{4}a^2\cot\frac{\pi}{9}=(9/2)ar = 9r^2\tan(\pi/9)
= (9/2)R^2\sin(2\pi/9)\simeq6.18182\,a^2.

a is the length of one of its sides.

Tilings

The regular enneagon can tessellate the euclidean tiling with gaps. These gaps can be filled with regular hexagons and isosceles triangles. In the notation of symmetrohedron this tiling is called H(*;3;*;[2]) with H representing *632 hexagonal symmetry in the plane.

Conway tiling dKH.png


Images for kids

  • 01-Neuneck Tomahawk Animation

    Nonagon, an animation from a neusis construction based on the angle trisection 120° by means of the Tomahawk, at the end 10 s break

  • 01 Neuneck-Archimedes

    Nonagon, a neusis construction based on a hexagon with trisection of the angle according to Archimedes

  • Regular enneagon symmetries

    Symmetries of a regular enneagon. Vertices are colored by their symmetry positions. Blue mirrors are drawn through vertices, and purple mirrors are drawn through edge. Gyration orders are given in the center.

See also

Kids robot.svg In Spanish: Eneágono para niños

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Nonagon Facts for Kids. Kiddle Encyclopedia.