Difference between revisions of "Quadrilateral"
From Conservapedia
DavidB4-bot (Talk | contribs) (→Classification of Quadrilaterals: clean up & uniformity) |
|||
| (9 intermediate revisions by 5 users not shown) | |||
| Line 1: | Line 1: | ||
| − | A quadrilateral is a [[ | + | A '''quadrilateral''' is a [[polygon]] with four sides. |
| + | |||
| + | 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. | ||
| + | |||
| + | ==Classification of Quadrilaterals== | ||
| + | |||
| + | The [[classification]] of quadrilaterals is complex, as there are several intersecting sub-categories: | ||
| + | * 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 | ||
| + | * A [[parallelogram]] has two pairs of opposite sides parallel (and equal) | ||
| + | * A [[rectangle]] has four right angles | ||
| + | * A [[rhombus]] has four equal sides | ||
| + | * A [[kite]] has two pairs of adjacent equal sides | ||
| + | * 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> | ||
| + | * An [[arrowhead]] is a re-entrant [[kite]] | ||
| + | * A [[square]] is both a [[rectangle]] and a [[rhombus]] | ||
| + | |||
| + | [[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:
- 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
- A parallelogram has two pairs of opposite sides parallel (and equal)
- A rectangle has four right angles
- A rhombus has four equal sides
- A kite has two pairs of adjacent equal sides
- A re-entrant quadrilateral has one internal angle greater than 180o; this may be contrasted with a convex quadrilateral in which all internal angles are less than 180o
- An arrowhead is a re-entrant kite
- A square is both a rectangle and a rhombus
