Quadrilateral

Overview

Euclidean geometry

Euclidean geometry is a mathematical system attributed to the Alexandrian Greek mathematician Euclid, which he described in his textbook on geometry: the Elements. Euclid's method consists in assuming a small set of intuitively appealing axioms, and deducing many other propositions from these...

, a

**quadrilateral**is a polygon

Polygon

In geometry a polygon is a flat shape consisting of straight lines that are joined to form a closed chain orcircuit.A polygon is traditionally a plane figure that is bounded by a closed path, composed of a finite sequence of straight line segments...

with four

**sides**(or 'edges') and four

**vertices**or

**corners**. Sometimes, the term

**quadrangle**is used, by analogy with triangle

Triangle

A triangle is one of the basic shapes of geometry: a polygon with three corners or vertices and three sides or edges which are line segments. A triangle with vertices A, B, and C is denoted ....

, and sometimes

**tetragon**for consistency with pentagon

Pentagon

In geometry, a pentagon is any five-sided polygon. A pentagon may be simple or self-intersecting. The sum of the internal angles in a simple pentagon is 540°. A pentagram is an example of a self-intersecting pentagon.- Regular pentagons :In a regular pentagon, all sides are equal in length and...

(5-sided), hexagon (6-sided) and so on. The word

**quadrilateral**is made of the words

**quad**(meaning "four") and

**lateral**(meaning "of sides").

The origin of the word quadrilateral is from the two Latin words "quadri", a variant of four, and "latus" meaning side.

Quadrilaterals are simple

Simple polygon

In geometry, a simple polygon is a closed polygonal chain of line segments in the plane which do not have points in common other than the common vertices of pairs of consecutive segments....

(not self-intersecting) or complex

Complex polygon

The term complex polygon can mean two different things:*In computer graphics, as a polygon which is neither convex nor concave.*In geometry, as a polygon in the unitary plane, which has two complex dimensions.-Computer graphics:...

(self-intersecting), also called crossed.

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