RD Sharma Solutions for Class 6 Chapter 13 "Quadrilaterals" Quadrilateral means "four sides" (quad means four, lateral means side). The figure which is obtained by four line segments and three vertices are called quadrilaterals. A Quadrilateral has four-sides, it is 2-dimensional (a flat shape), closed (the lines join up), and has straight sides. It describes the definition of Quadrilaterals, Elements of a Quadrilateral, Types of Quadrilaterals, and Sum of Angles of a Quadrilateral.