Air casan a ' cuideachadh dhut obrachadh a-mach an sgìre agus perimeter of a quadrilateral.
San quadrilateral tha geometric t-suim (polygon) a bheil na ceithir points (vertices), no triùir a tha collinear, agus ceithir gradients (air gach taobh), gu cunbhalach a ' ceangal na points.
Mhothachadh eadar convex agus nonconvex quadrangles, neo-convex quadrilateral s urrainn dhut a cho-intersecting.
An quadrangle chan eil eadar-ghearr fhèin ris an canar sìmplidh a th ' ann, gu tric fo the term "quadrangle" ' s e a-mhàin sìmplidh quadrilaterals.