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