Nonagon
Regular nonagon
All sides of a regular nonagon are the same length. Each corner is 140°. All corners added together equal 1260°.
Area
The amount of space a regular nonagon takes up is
- [math]\displaystyle{ A = \frac{9}{4}a^2\cot\frac{\pi}{9}=(9/2)ar = 9r^2\tan(\pi/9) }[/math]
- [math]\displaystyle{ = (9/2)R^2\sin(2\pi/9)\simeq6.18182\,a^2. }[/math]
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.
Nonagon Media
Nonagon, an animation from a neusis construction based on the angle trisection 120° by means of the Tomahawk, at the end 10 s break
Nonagon, a neusis construction based on a hexagon with trisection of the angle according to Archimedes
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.
en:8-simplex family graph in A8 Coxeter plane
Socha, Garsų Gaudyklė, Gintaro ilanka, Neringa, Litva
