22 Distance between the two planes: 2x + 3y + 4z = 4 and 4x + 6y + 8z = 12 is
(A) 2 units
(B) 4 units
(C) 8 units
(D)
2
29
 units
23 The planes: 2x – y + 4z = 5 and 5x – 2 5y + 10z = 6 are
(A) Perpendicular
(B) Parallel
(C) intersect y-axis
(D) passes through 
5
0,0,
4






Summary
� Direction cosines of a line are the cosines of the angles made by the line
with the positive directions of the coordinate axes