Difference between revisions of "Quadrilateral"

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(Classification of Quadrilaterals: clean up & uniformity)
 
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A quadrilateral is a [[Polygon]] with four sides.
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A '''quadrilateral''' is a [[polygon]] with four sides.
  
[[Category:Geometry]]
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As a consequence of the definition, the sum of the angles in a quadrilateral equals 360<sup>o</sup>, and all quadrilaterals are capable of [[tessellation|tessellating]] an [[infinite]] plane.
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==Classification of Quadrilaterals==
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The [[classification]] of quadrilaterals is complex, as there are several intersecting sub-categories:
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* A (British) [[trapezium]] or (American) [[trapezoid]] has one pair of opposite sides parallel. A version of this called the [[isosceles trapezium]] has the other pair of opposite sides equal
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* A [[parallelogram]] has two pairs of opposite sides parallel (and equal)
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* A [[rectangle]] has four right angles
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* A [[rhombus]] has four equal sides
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* A [[kite]] has two pairs of adjacent equal sides
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* A [[re-entrant quadrilateral]] has one internal angle greater than 180<sup>o</sup>; this may be contrasted with a [[convex quadrilateral]] in which all internal angles are less than 180<sup>o</sup>
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* An [[arrowhead]] is a re-entrant [[kite]]
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* A [[square]] is both a [[rectangle]] and a [[rhombus]]
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[[Category:Plane Geometry]]

Latest revision as of 12:03, 13 July 2016

A quadrilateral is a polygon with four sides.

As a consequence of the definition, the sum of the angles in a quadrilateral equals 360o, and all quadrilaterals are capable of tessellating an infinite plane.

Classification of Quadrilaterals

The classification of quadrilaterals is complex, as there are several intersecting sub-categories: