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