Find the ratio in which the YZ-plane divides the line segment formed by joining the points (–2, 4, 7) and (3, –5, 8).
Find the ratio in which the join of P (2, 1, -1) and Q (3, 2, 4) is divided by XY-plane.
Let XY-plane divides PQ in ratio k : 1 at point R.
Point R isÂ
Since R lies on XY-plane.
∴ z co-ordinate = 0  Â
           Â
       Â
Hence, the ratio is  internally.