Enneagram

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Enneagram
Rank2
TypeRegular
Notation
Bowers style acronymEng
Coxeter diagramx9/2o ()
Schläfli symbol{9/2}
Elements
Edges9
Vertices9
Vertex figureDyad, length 2cos(2π/9)
Measures (edge length 1)
Circumradius
Inradius
Area
Angle100°
Central density2
Number of external pieces18
Level of complexity2
Related polytopes
ArmyEn, edge length
DualEnneagram
ConjugatesEnneagon, great enneagram
Convex coreEnneagon
Abstract & topological properties
Flag count18
Euler characteristic0
OrientableYes
Properties
SymmetryI2(9), order 18
ConvexNo
NatureTame

The enneagram is a non-convex polygon with 9 sides. Its created by taking the first stellation of an enneagon. A regular enneagram has equal sides and equal angles.

It is one of two regular 9-sided star polygons, the other being the great enneagram. The name "enneagram" is often used to describe either of these two shapes.

Vertex coordinates[edit | edit source]

Coordinates for a regular enneagram of edge length , centered at the origin, are:

  • ,
  • ,
  • ,
  • ,
  • .

External links[edit | edit source]