Show that the points P(-2, 3, 5), Q(1, 2, 3) and R(7, 0, -1) are collinear.

Show that the points A(1, 2, 7), B(2, 6, 3) and C(3, 10, -1) are collinear.

Using section formula, show that the points A(2, -3, 4), B(-1, 2, 1) and C(0,1/3,2) are collinear.

Show that the points A(2, 3, -4), B(1, - 2, 3) and C(3, 8, - 11) are collinear.

Prove by using distance formula that the points P(1, 2, 3), Q(-1, -1, -1) and R(3, 5, 7) are collinear.

Find the direction cosines of the line joining the two points P(-2, 4, -5) and Q(1, 2, 3). 6. Prove that the points (1, 2, 3), (3, 1, 7) and (7, -1, 15) are collinear.

Show that the points (2, 3, 4), (- 1, - 2, 1), (5, 8, 7) are collinear.

Using distance formula, show that the points (1,5), (2,4) and (3,3) are collinear.

Show that the point P(a, b + c), Q(b, c +a) and R(c, a + b) are collinear.

Show that the point A(1, -1, 3), B(2, -4, 5) and C(5, -13, 11) are collinear.