Class 12 chapter 1 Relations and functions Basic concepts of topic relations and functions class XII chapter 1 of mathematics. Equivalence relations, different types of functions, composition and inverse of functions. Introduction In class 11 we have studied about Cartesian product of two sets, relations, functions, domain, range and co-domains. Now in this chapter we have studied about the different types of relations, different types of functions, composition of functions and invertible functions. Relations A relation R from set A to set B is the subset of Cartesian product A x B. In Cartesian product A x B number of relations equal to the number of subsets. Domain Set of all first elements of the ordered pairs in the relation R is called its domain. Range Set of all second elements of the ordered pairs in the relation R is called its range. In any ordered pair second element is also called the image of first element. Types of relation