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A '''polygon''' is a union of disjoint [[line segment]]s that is [[path-connected]].
A '''polygon''' is a union of disjoint [[line segment]]s that is [[connectedness|connected]].
A polygon is described as "regular" if all its sides and their included angles are equal.
A [[regular polygon]] has all sides equal and all angles equal.
Types, by number of sides.
Types, by number of sides.
# [[Heptagon]] - seven sided. Some coins have been been heptagonal.
# [[Heptagon]] - seven sided. Some coins have been been heptagonal.
# [[Octagon]] - eight sided, used for [[stop sign]]s in the U.S.
# [[Octagon]] - eight sided, used for [[stop sign]]s in the U.S.
# Higher orders of polygons are: [[nonagon]] (9-sided), [[decagon]] (10-sided), [[unodecagon]] (11-sided), [[duodecagon]] (12-sided) etc.
[[Category:Geometry]]
# 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.
==Formulas==
The [[perimeter]] of a regular polygon is equal to <math>n sin\frac{180}{n} (2) (r)</math>, where ''r'' equals the length of the radius.<br>
The [[area]] of a regular polygon is equal to <math>n sin\frac{180}{n}cos\frac{180}{n}(r^2)</math>
[[Category:Plane Geometry]]