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!
