A relation `\rho` defined on plane `\mathbb{R}^2` by : `\rho = [ {(a,b),(c,d)} \in \mathbb{R}^2 \times \mathbb{R}^2 | a^2+b^2 = c^2+d^2 ]`. Show that the relation `\rho` is an equivalence relation on `\mathbb{R}^2`.