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.

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The sum of the measures of the angles of a convex polygon with n sides is (n - 2)180.

Polygon Angle Calculator
Sides of polygon:
Each exterior angle:
Each interior angle: