Geometry and TrigonometryPlane Geometry |
What are the names given to regular polygons? |
Polygons are classified according to the number of sides they have. A polygon with n sides is called an n-gon. The following lists some of the names of polygons, depending on the number of sides. It is also possible to substitute “n-gon,” when the name is not known (for example 14-gon or 20-gon).
| Sides | Polygon Name |
| 3 | trigon or triangle |
| 4 | quadrilateral or tetragon |
| 5 | pentagon |
| 6 | hexagon |
| 7 | heptagon |
| 8 | octagon |
| 9 | nonagon or enneagon |
| 10 | decagon |
| 11 | hendecagon or undecagon (even less frequently as unidecagon) |
| 12 | dodecagon |
| 13 | tridecagon or triskaidecagon |
| 14 | tetradecagon or tetrakaidecagon |
| 15 | pentadecagon or pentakaidecagon |
| 16 | hexadecagon or hexakaidecagon |
| 17 | heptadecagon or heptakaidecagon |
| 18 | octadecagon or octakaidecagon |
| 19 | enneadecagon or enneakaidecagon |
| 20 | icosagon |
| 30 | triacontagon |
| 40 | tetracontagon |
| 50 | pentacontagon |
| 60 | hexacontagon |
| 70 | heptacontagon |
| 80 | octacontagon |
| 90 | enneacontagon |
| 100 | hectogon or hecatontagon |
| 1,000 | chiliagon |
| 10,000 | myriagon |
Some texts list a two-sided polygon as a “digon,” but this is only meant for theoretical mathematics. If you feel like making up your own name, try constructing some sided polygons. For example, a 46-sided polygon could be called a tetracontakai-hexagon, or a combination of “tetracon-tagon” + “kai” (often used in combining names) + “hexagon.” To shorten such long names, mathematicians often use “n-gon” to simplify matters; thus, 46 would be 46-gon a much easier name to remember and even say.
The parts of a polygon.