Compound of three triangles

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Compound of three triangles
Rank2
TypeRegular
Notation
Bowers style acronymFen
Schläfli symbol{9/3}
Elements
Components3 triangles
Edges9
Vertices9
Vertex figureDyad, length 1
Measures (edge length 1)
Circumradius
Inradius
Area
Angle60º
Central density3
Number of external pieces18
Level of complexity2
Related polytopes
ArmyEn, edge length
DualCompound of three triangles
ConjugateNone
Convex coreEnneagon
Abstract & topological properties
Flag count18
Euler characteristic0
OrientableYes
Properties
SymmetryI2(9), order 18
ConvexNo
NatureTame

The fissal enneagram, or fen, is a polygon compound composed of 3 triangles. As such it has 9 edges and 9 vertices.

It is the second stellation of the enneagon.

Its quotient prismatic equivalent is the 9-3 step prism, which is four-dimensional.

Vertex coordinates[edit | edit source]

Coordinates for the vertices of a fissal enneagram of edge length 1 centered at the origin are given by:

External links[edit | edit source]