# Part - 3 Lecture - 2 Chapter 1 Relations and Functions

“Try to be a rainbow in someone’s cloud.” —*Maya Angelou*

**Question 10.** Let A = {0, 1, 2, 3, 4} and define a relation R on A as follows: R = {(0, 0), (0, 4), (1, 1), (1, 3), (2, 2), (3, 1), (3, 3), (4, 0), (4, 4)}. As R is an equivalence relation on A. Find the distinct equivalence classes of R.

**Question 11.** Let R be the relation on set A {0, 1, 2, 3, …, 10} given by R = {(a, b) : (a – b) is divisible by 4}. Show that R is an equivalence relation. Also, write all elements related to 4.

**Question 8.** Show that the relation R defined in the set A of all polygons as R = {(P_{1}, P_{2}): P_{1} and P_{2} have same number of sides}, is an equivalence relation. What is the set of all elements in A related to the right angle triangle T with sides 3, 4 and 5?

**Question 9.** Let L be the set of all lines in XY plane and R be the relation in L defined as R = {(L_{1}, L_{2}) : L_{1} is parallel to L_{2} }. Show that R is an equivalence relation. Find the set of all lines related to the line y = 2x + 4.