Which of the following can not be the direction cisines of a line?

Options

A. `sqrt((1)/(5)),-sqrt((1)/(2)),sqrt((3)/(10))`
B. `(1)/(sqrt(3)),(-1)/(sqrt(3)),(1)/(sqrt(3))`
C. `(1)/(sqrt(2)),(-1)/(sqrt(2)),(-1)/(sqrt(2))`
D. `(1)/(sqrt(2)),(-1)/(sqrt(2)),0`

Answer

C

Explanation

We know that, `l^(2)+m^(2)+n^(2)=1`
since, `((1)/(sqrt(2)))^(2)+((-1)/(sqrt(2)))^(2)+((-1)/(sqrt(2)))^(2)`
`=(1)/(2)+(1)/(2)+(1)/(2)=(3)/(2)ne1`