Sajeroning géomètri (Euclidean, quadrilateral utawa quarangle utawa tetragon iku sawijining wangun segi akèh polygon kanthi papat sisi (utawa 'rusuk') lan papat pojok.  Tembung quadrilateral asal saka tembung quad (tegesé "papat") lan lateral (tegesé "sisih").

Quadrilateral iku poligon sing bisa awujud prasaja utawa komplèks. Quadrilateral bisa awujud convex utawa concave.

Rujukan

Pranala njaba 

 
Compendium Geometry Analytic Geometry of Quadrilaterals
Quadrilaterals Formed by Perpendicular Bisectors, Projective Collinearity and  Interactive Classification of Quadrilaterals from cut-the-knot
Definitions and examples of quadrilaterals and Definition and properties of tetragons from Mathopenref
 A (dynamic) Hierarchical Quadrilateral Tree  at Dynamic Geometry Sketches 
 An extended classification of quadrilaterals  at Dynamic Math Learning Homepage 
The role and function of a hierarchical classification of quadrilaterals  by Michael de Villiers

 
Poligon