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Enneagram (geometry)

In geometry, an enneagram (🟙 U+1F7D9) is a nine-pointed plane figure. It is sometimes called a nonagram, nonangle, or enneagon.

The word 'enneagram' combines the numeral prefix ' with the Greek suffix '. The gram suffix derives from γραμμῆ (grammē) meaning a line.

Regular enneagram

A regular enneagram is a 9-sided 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:

  • One form connects every second point and is represented by the Schläfli symbol {9/2}.
  • The other form connects every fourth point and is represented by the Schläfli symbol {9/4}.

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. (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.

Other enneagram figures

The nine-pointed star or enneagram can also symbolize the nine gifts or fruits of the Holy Spirit.

In popular culture

  • The heavy metal band Slipknot previously used the {9/3} star figure enneagram and currently uses the {9/4} polygon as a symbol. The prior figure can be seen on the cover of their album All Hope Is Gone.
  • The symbol of Eldia from Attack on Titan is an irregular enneagram, representing the nine Titan powers.

See also

References

Bibliography

External links