Find the direcation cosines of a line that pass through the points P(2, 4, 6) and Q (5, 1, 11) and
is so directed that it mekes an acute angle with the positive direction of y-axis.

Explanation

The direction ratios of the line sement joining P(2, 4, 6) and Q(5 , 1, 11) are
` 5 - 1 , 1 - 4 , 11 - 6 `
i.e., 4, ` - 3, 5 `
_Thus the direction cosines are
`pm (4)/(sqrt(16+9+25)),pm(-3)/(sqrt(16 + 9 + 25)) ,pm(5)/(sqrt(16 + 9 + 25)) `
i.e.,` pm (4)/(5sqrt(2)),pm(-3)/(5sqrt(2)),pm(5)/(5sqrt(2))`
Since the line makes an acute angle with y-axis, hence the required direction cosines of the
line segment are given by
`-(2sqrt(2))/(5), (3sqrt(2))/(10),(sqrt(2))/(2)`