Show that the following points are the vertices of a rectangle:
(i) A(-4, -1), B (-2, -4), C(4, 0) and D(2, 3) (ii) A(2, -2), B(14, 10), C(11, 13) and D(-1, 1) (iii) A(0, -4), B(6, 2), C(3, 5) and D(-3, -1)