Quadrilateral

Quadrilateral

In Euclidean plane geometry, a quadrilateral is a polygon with four edges (or sides) and four vertices or corners.

Video: What is a Quadrilateral? – Geometric Shapes

Sometimes, the term quadrangle is used, by analogy with triangle, and sometimes tetragon for consistency with pentagon (5-sided), hexagon (6-sided) and so on.

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

Quadrilaterals are simple (not self-intersecting) or complex (self-intersecting), also called crossed. Simple quadrilaterals are either convex or concave.

The interior angles of a simple (and planar) quadrilateral ABCD add up to 360 degrees of arc, that is

This is a special case of the n-gon interior angle sum formula (n − 2) × 180°

Simple quadrilaterals

Any quadrilateral that is not self-intersecting is a simple quadrilateral.

Video: Quadrilaterals - 04 Simple and Complex Quadrilateral

Convex quadrilaterals

Euler diagram of some types of simple quadrilaterals. (UK) denotes British English and (US) denotes American English.

Video: Convex and Concave Quadrilateral

In a convex quadrilateral, all interior angles are less than 180° and .....

 

 

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