Naming Polygons
The word "polygon" comes from Late Latin polygōnum (a noun), from Greek πολύγωνον (polygōnon/polugōnon), noun use of neuter of πολύγωνος (polygōnos/polugōnos, the masculine adjective), meaning "many-angled". Individual polygons are named (and sometimes classified) according to the number of sides, combining a Greek-derived numerical prefix with the suffix -gon, e.g. pentagon, dodecagon. The triangle, quadrilateral or quadrangle, and nonagon are exceptions. For large numbers, mathematicians usually write the numeral itself, e.g. 17-gon. A variable can even be used, usually n-gon. This is useful if the number of sides is used in a formula.
Some special polygons also have their own names; for example the regular star pentagon is also known as the pentagram.
| Name | Edges | Remarks |
|---|---|---|
| henagon (or monogon) | 1 | In the Euclidean plane, degenerates to a closed curve with a single vertex point on it. |
| digon | 2 | In the Euclidean plane, degenerates to a closed curve with two vertex points on it. |
| triangle (or trigon) | 3 | The simplest polygon which can exist in the Euclidean plane. |
| quadrilateral (or quadrangle or tetragon) | 4 | The simplest polygon which can cross itself. |
| pentagon | 5 | The simplest polygon which can exist as a regular star. A star pentagon is known as a pentagram or pentacle. |
| hexagon | 6 | Avoid "sexagon" = Latin + Greek. |
| heptagon | 7 | Avoid "septagon" = Latin + Greek. The simplest polygon such that the regular form is not constructible with compass and straightedge. However, it can be constructed using a Neusis construction. |
| octagon | 8 | |
| enneagon or nonagon | 9 | "Nonagon" is commonly used but mixes Latin with Greek. Some modern authors prefer "enneagon", which is pure Greek. |
| decagon | 10 | |
| hendecagon | 11 | Avoid "undecagon" = Latin + Greek. The simplest polygon such that the regular form cannot be constructed with compass, straightedge, and angle trisector. |
| dodecagon | 12 | Avoid "duodecagon" = Latin + Greek. |
| tridecagon (or triskaidecagon) | 13 | |
| tetradecagon (or tetrakaidecagon) | 14 | |
| pentadecagon (or quindecagon or pentakaidecagon) | 15 | |
| hexadecagon (or hexakaidecagon) | 16 | |
| heptadecagon (or heptakaidecagon) | 17 | |
| octadecagon (or octakaidecagon) | 18 | |
| enneadecagon (or enneakaidecagon or nonadecagon) | 19 | |
| icosagon | 20 | |
| triacontagon | 30 | |
| hectogon | 100 | "hectogon" is the Greek name (see hectometer), "centagon" is a Latin-Greek hybrid; neither is widely attested. |
| chiliagon | 1000 | René Descartes, Immanuel Kant, David Hume, and others have used the chiliagon as an example in philosophical discussion. |
| myriagon | 10,000 | |
| megagon | 1,000,000 | As with René Descartes' example of the chiliagon, the million-sided polygon has been used as an illustration of a well-defined concept that cannot be visualised. The megagon is also used as an illustration of the convergence of regular polygons to a circle. |
| apeirogon | A degenerate polygon of infinitely many sides |
Read more about this topic: Polygon
Famous quotes containing the word naming:
“The night is itself sleep
And what goes on in it, the naming of the wind,
Our notes to each other, always repeated, always the same.”
—John Ashbery (b. 1927)