Find the direction cosines of the line joining the points (2, 1, 2) and (4, 2, 0).
A line makes angles of 45° and 60° with the positive axes of x and y respectively. What angle does it make with the positive axis of z?
Find the length of the projection of the line segment joining the points P (3, -1, 2) and Q(2, 4, -1) on the line with direction ratios -1, 2, -2.