A regular polygon has all sides equal and all angles equal.
Types, by number of sides.
- There is no such mathematical entity as a one sided polygon in a plane. (For higher dimensional analogies, see Mobius strip and Klein bottle.)
- As with the one-sided polygon, there is no such thing as a two-sided polygon. (This would be two overlapping line segments.)
- Triangle - three sided, see isosceles triangle, equilateral triangle, right triangle
- Quadrilateral - four sided, see also square, rectangle, rhombus, and trapezoid
- Pentagon - five sided. The most famous one houses the Department of Defense.
- Hexagon - six sided, the shape of a bee hive cell, also used in some board games
- Heptagon - seven sided. Some coins have been been heptagonal.
- Octagon - eight sided, used for stop signs in the U.S.
- Higher orders of polygons are: nonagon (9-sided), decagon (10-sided), unodecagon (11-sided), duodecagon (12-sided) etc.
- Polygons of higher orders than the duodecagon are often named n-gons, where n is the amount of its sides. For example, a 42-gon would be a polygon with 42 sides.