Polygons: How Many Sides?

A geometrical figure with three or more sides is called a polygon or a polyhedron. Here are the names for some polygons.

3triangle, trigon
4quadrilateral, tetragon
5pentagon
6hexagon
7heptagon
8octagon
9nonagon, enneagon
10decagon
11hendecagon
12dodecagon, duodecagon
13triskaidecagon, tridecagon
14tetrakaidecagon, tetradecagon
15pentadecagon
16hexadecagon
17heptadecagon
18octadecagon
19enneadecagon
20icosagon

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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