Enneagram  

Edges and vertices  9 
Symmetry group  Dihedral (D9) 
Internal angle (degrees)  100° {9/2} 20° {9/4} 
Star polygons 


In geometry, an enneagram ( U+1F7D9) is a ninepointed plane figure. It is sometimes called a nonagram, nonangle, or enneagon.^{[1]}
The word 'enneagram' combines the numeral prefix ennea with the Greek suffix gram. The gram suffix derives from γραμμῆ (grammē) meaning a line.^{[2]}
A regular enneagram is a 9sided star polygon. It is constructed using the same points as the regular enneagon, but the points are connected in fixed steps. Two forms of regular enneagram exist:
There is also a star figure, {9/3} or 3{3}, made from the regular enneagon points but connected as a compound of three equilateral triangles.^{[3]}^{[4]} (If the triangles are alternately interlaced, this results in a Brunnian link.) This star figure is sometimes known as the star of Goliath, after {6/2} or 2{3}, the star of David.^{[5]}
Compound  Regular star  Regular compound 
Regular star 

Complete graph K_{9} 
{9/2} 
{9/3} or 3{3} 
{9/4} 
The final stellation of the icosahedron has 2isogonal enneagram faces. It is a 9/4 wound star polyhedron, but the vertices are not equally spaced. 
The Fourth Way teachings and the Enneagram of Personality use an irregular enneagram consisting of an equilateral triangle and an irregular hexagram based on 142857. 
The Bahá'í ninepointed star 
A 9/3 enneagram 
The ninepointed star or enneagram can also symbolize the nine gifts or fruits of the Holy Spirit.^{[6]}
Bibliography
Triangles  

Quadrilaterals  
By number of sides 
 
Star polygons  
Classes 