 Hello and welcome to the session, let us understand the following question which says, sure that the relation are defined in the set A of all triangles as R is equal to T1 and T2 such that T1 is similar to T2 is equivalence relation. Consider three right triangles T1 with sides 3, 4, 5, T2 with sides 5, 12, 13 and T3 with sides 6, 10, 8 which triangles among T1, T2 and T3 are related. Now let us proceed on to the solution. Given to us is is equal to set of all triangles is equal to R of T1 and T2 such that T1 is similar to T2 and let us check for reflexivity. We know any triangle is similar to itself. T and T belongs to R for all T belongs to A. Therefore R is reflexive. Let us check for symmetry T1 and T2 belongs to R so we can say similar to T1, T1 belongs to R. Therefore T1 and T2 belongs to R and T2 and T3 belongs to R. We observe that 5 by 10. This question bye and have a nice day.