Using distance formula prove that the following points are collinear
(i) A(4, -3, -1), B(5, -7, 6) and C(3, 1, -8)
(ii) P(0,7, -7), Q(1, 4, -5) and R(-1, 10, -9)
(iii) A(3, -5, 1), B(-1, 0, 8) and C(7, -10, -6)