RS Aggarwal Solutions for Class 7 Chapter 20 Mensuration explains the concept of Area and Parameter of Rectangles, Squares, Triangle, circumference and Area of Circle. Mensuration is the skill of measuring the length of lines, areas of surfaces, and volumes of solids from simple data of lines and angles—mensuration deals with length, area and volume of different kinds of shapes, both 2D and 3D. Mensuration is a formula oriented topic. There are specific formulas for various parameters; we put the values in these Mensuration formulas and get the desired answers. It is generally used where geometrical figures are concerned, where one has to determine various physical quantities such as perimeter, area, volume or length. In this chapter, we shall review the problems related to them and further take up the areas of parallelograms, triangles and trapezia, etc.