Show that the relation $R$ defined in the set $A$ of all triangles as $R = \{(T_1, T_2) : T_1 \text{ is similar to } T_2\}$, is equivalence relation. Consider three right angle triangles $T_1$ with sides $3, 4, 5$, $T_2$ with sides $5, 12, 13$ and $T_3$ with sides $6, 8, 10$. Which triangles among $T_1, T_2$ and $T_3$ are related? [Competency]