Octadecagram
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Octadecagram | |
---|---|
Rank | 2 |
Type | Regular |
Notation | |
Bowers style acronym | Odge |
Coxeter diagram | x18/5o () |
Schläfli symbol | {,18/5} |
Elements | |
Edges | 18 |
Vertices | 18 |
Vertex figure | Dyad, length 2cos(5π/18) |
Measures (edge length 1) | |
Circumradius | |
Inradius | |
Area | |
Angle | 80° |
Central density | 5 |
Number of external pieces | 36 |
Level of complexity | 2 |
Related polytopes | |
Army | Od, edge length |
Dual | Octadecagram |
Conjugates | Octadecagon, great octadecagram |
Convex core | Octadecagon |
Abstract & topological properties | |
Flag count | 36 |
Euler characteristic | 0 |
Schläfli type | {18} |
Orientable | Yes |
Properties | |
Symmetry | I2(18), order 36 |
Convex | No |
Nature | Tame |
The octadecagram, or odge, is a non-convex polygon with 18 sides. It's created by taking the fourth stellation of an octadecagon. A regular octadecagram has equal sides and equal angles.
It is one of two regular 18-sided star polygons, the other being the great octadecagram.
It is the uniform quasitruncation of the great enneagram.