RS Aggarwal Solutions for Class 9 Chapter 10 “Quadrilaterals”, the prefix “quad-” means “four,” and “lateral” is derived from the Latin word for “side.” So a quadrilateral is a four-sided polygon. In Euclidean plane geometry, a quadrilateral is a polygon with four edges and four vertices. Other names for quadrilateral include quadrangle, tetragon, and 4-gon. Quadrilaterals majorly help architects to design buildings based on the utilization of space. They are used in electronic devices like laptops, mobiles, TV etc. and in stationery items like copies, books, chart papers etc. The Chapter describes about the various types of quadrilaterals, results on parallelograms, rectangles, rhombuses and square and midpoint theorem.