A relation $R$ on $A$ = {1, 2, 3} defined by $R$ = { (1, 1) (1, 2) (3, 3) } is not symmetric. Why?

Relation $R$ on $A$ is defined by R={(1,1)(1,2)(3,3)}

The relation $R$ is said to be symmetric, if (a,b) belongs to R then (b,a) should also be in R.

Here (1,2) $\in R$ but (2,1) $\notin R$.

Therefore relation R does not satisfy symmetric condition.