1.

Write the direction cosines of the vector `-2 hat i+ hat j-5 hat k`A. `-2, 1, -5`B. `(1)/(3),(-1)/(6),(-5)/(6)`C. `(2)/(sqrt(30)), (1)/(sqrt(30)),(5)/(sqrt(30))`D. `(-2)/(sqrt(30)),(1)/(sqrt(30)),(-5)/(sqrt(30))`

Answer» Correct Answer - D
`|vec(a)|=sqrt((-2)^(2)+1^(2)+(-5)^(2))=sqrt(3)`.
`:.` direction cosines of `vec(a)` are `(-2)/(sqrt(30)),(1)/(sqrt(30)), (-5)/(sqrt(30))`.


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