From the point P(a, b, c),let perpendiculars PL and PM be drawn to YOZ and ZOX planes, respectively. Then the
equation of the plane OLM is
Coordinates of L and M are (0, b, c) and (a,0, c), respectively.
Therefore, the equation of the plane passing through (0, 0, 0), (0, b, c) and (a, 0, c) is