Show that the parallelogram formed by `ax+by+c=0, a_1 x+ b_1 y+c=0, ax+by+c_1 =0 and a_1 x+b_1 y+c_1 =0` will be a rhombus if `a^2 +b^2 = (a_1)^2 + (b_1)^2`.