Given that the direction ratio of the line are `-18,12,-4`.
Here, `a = - 18, b = 12` and `c = -4`,
Then direction cosines of the line are
`=((a)/(sqrt(a^(2)+b^(2)+c^(2))),(b)/(sqrt(a^(2)+b^(2)+c^(2))),(C)/(sqrt(a^(2)+b^(2)+c^(2))))`
`= ((-18)/(sqrt((-18)^(2)+(12)^(2)+(-4)^(2))), (12)/(sqrt((-18)^(2)+(12)^(2)+(-4)^(2))),(-4)/(sqrt((-18)^(2)+(12)^(2)+(-4)^(2))))`
`= ((-18)/(sqrt(484)),(12)/(sqrt(484)),(-4)/(sqrt(484)))`
`= ((-18)/(22),(12)/(22),(-4)/(22)) = (-(9)/(11),(6)/(11),(-2)/(11))`
Therefore, direction cosines of the line are `- (9)/(11),(6)/(11)` and `(-2)/(11)`.
