Solution Let the coordinates of the foot of the perpendicular P from the origin to the
plane is (x1, y1, z1) (Fig 11 11) Then, the direction ratios of the line OP are
x1, y1, z1 Writing the equation of the plane in the normal
form, we have
2
3
4
6
29
29
29
29
x
y
z
−
+
=
where, 
2
3
4
,
,
29
29
29
−
 are the direct ion
cosines of the OP