Enneagram (geometry) explained
| Enneagram |
| Edges: | 9 |
| Symmetry: | Dihedral (D9) |
| Angle: | 100°
20° |
In geometry, an enneagram (U+1F7D9) is a nine-pointed 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]
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 .
- The other form connects every fourth point and is represented by the Schläfli symbol .
There is also a star figure, or 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 or 2, the star of David.[5]
Other enneagram figures
The nine-pointed star or enneagram can also symbolize the nine gifts or
fruits of the Holy Spirit.
[6] In popular culture
- The heavy metal band Slipknot previously used the star figure enneagram[7] and currently uses the polygon as a symbol. The prior figure can be seen on the cover of All Hope Is Gone.
See also
References
Bibliography
External links
Notes and References
- Web site: Between a square rock and a hard pentagon: Fractional polygons. 28 September 2017.
- https://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Dgrammh%2F γραμμή
- [Branko Grünbaum|Grünbaum, B.]
- [Branko Grünbaum|Grünbaum, B.]
- Web site: Nonagram. Eric W.. Weisstein. Eric W. Weisstein. mathworld.wolfram.com.
- Our Christian Symbols by Friedrich Rest (1954),, page 13.
- Web site: slipknot. eBay.
