Polygons: How Many Sides?
Updated June 26, 2019 |
Infoplease Staff
A geometrical figure with three or more sides is called a polygon or a polyhedron. Here are the names for some polygons.
3 | triangle, trigon |
4 | quadrilateral, tetragon |
5 | pentagon |
6 | hexagon |
7 | heptagon |
8 | octagon |
9 | nonagon, enneagon |
10 | decagon |
11 | hendecagon |
12 | dodecagon, duodecagon |
13 | triskaidecagon, tridecagon |
14 | tetrakaidecagon, tetradecagon |
15 | pentadecagon |
16 | hexadecagon |
17 | heptadecagon |
18 | octadecagon |
19 | enneadecagon |
20 | icosagon |
How Many Angles?
A polygon has as many angles as it has sides. For example, a triangle has 3 sides and 3 angles. A pentagon has 5 sides and 5 angles. An octadecagon has 18 sides and 18 angles!
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