Polygons
A polygon is closed plane figure formed by the joining of three or more
straight lines. A regular polygon is one that has equal sides and equal
interior angles.
Regular Polygons |
Sides |
Name |
Interior
Angles |
Exterior
Angles |
3 |
Triangle |
60.00° |
120.00° |
4 |
Quadrilateral |
90.00° |
90.00° |
5 |
Pentagon |
108.00° |
72.00° |
6 |
Hexagon |
120.00° |
60.00° |
7 |
Heptagon |
128.57° |
51.43° |
8 |
Octagon |
135.00° |
45.00° |
9 |
Nonagon |
140.00° |
40.00° |
10 |
Decagon |
144.00° |
36.00° |
11 |
Hendecagon |
147.27° |
32.73° |
12 |
Dodecagon |
150.00° |
30.00° |
13 |
Triskaidecagon |
152.31° |
27.69° |
14 |
Tetrakaidecagon |
154.29° |
25.71° |
15 |
Pendedecagon |
156.00° |
24.00° |
16 |
Hexdecagon |
157.50° |
22.50° |
17 |
Heptdecagon |
158.82° |
21.18° |
18 |
Octdecagon |
160.00° |
20.00° |
19 |
Enneadecagon |
161.05° |
18.95° |
20 |
Icosagon |
162.00° |
18.00° |
30 |
Triacontagon |
168.00° |
12.00° |
40 |
Tetracontagon |
171.00° |
9.00° |
50 |
Pentacontagon |
172.80° |
7.20° |
60 |
Hexacontagon |
174.00° |
6.00° |
70 |
Heptacontagon |
174.86° |
5.14° |
80 |
Octacontagon |
175.50° |
4.50° |
90 |
Enneacontagon |
176.00° |
4.00° |
100 |
Hectogon |
176.40° |
3.60° |
1,000 |
Chiliagon |
179.64° |
0.36° |
10,000 |
Myriagon |
179.96° |
0.04° |
Note: After about 6 sides mathematicians usually refer to
these polygons as
n-gons, so a 23 sided polygon would be called a 23-gon.
The sum of the measures of the angles of a convex polygon with n sides is (n - 2)180.