Difference between revisions of "Polygon"

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A '''polygon''' is a union of disjoint [[line segment]]s that is [[connectedness|connected]].
 
A '''polygon''' is a union of disjoint [[line segment]]s that is [[connectedness|connected]].
  
A [[Regular polygon]] has all sides equal and all angles equal.
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A [[regular polygon]] has all sides equal and all angles equal.
  
 
Types, by number of sides.
 
Types, by number of sides.
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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 [[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>
 
The [[area]] of a regular polygon is equal to <math>n sin\frac{180}{n}cos\frac{180}{n}(r^2)</math>
[[Category:Geometry]]
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[[Category:Plane Geometry]]

Latest revision as of 02:05, January 16, 2009

A polygon is a union of disjoint line segments that is connected.

A regular polygon has all sides equal and all angles equal.

Types, by number of sides.

  1. There is no such mathematical entity as a one sided polygon in a plane. (For higher dimensional analogies, see Mobius strip and Klein bottle.)
  2. As with the one-sided polygon, there is no such thing as a two-sided polygon. (This would be two overlapping line segments.)
  3. Triangle - three sided, see isosceles triangle, equilateral triangle, right triangle
  4. Quadrilateral - four sided, see also square, rectangle, rhombus, and trapezoid
  5. Pentagon - five sided. The most famous one houses the Department of Defense.
  6. Hexagon - six sided, the shape of a bee hive cell, also used in some board games
  7. Heptagon - seven sided. Some coins have been been heptagonal.
  8. Octagon - eight sided, used for stop signs in the U.S.
  9. Higher orders of polygons are: nonagon (9-sided), decagon (10-sided), unodecagon (11-sided), duodecagon (12-sided) etc.
  10. 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 , where r equals the length of the radius.
The area of a regular polygon is equal to