Write the direction cosines of the vectors `(-2hati + hatj - 5hatk)`.

1.	Write the direction cosines of the vectors `(-2hati + hatj - 5hatk)`.
Answer» The given vector is `veca = (-2hati + hatj -5hatk)`. Direction ratios of `veca` are `-2,1,-5`. `\|veca\| = sqrt((-2)^(2) + 1^(2) +(-5)^(2)) = sqrt(30)`. Hence, the direction cosines of `veca` are `(-2)/(sqrt(30)), (1)/(sqrt(30)), (-5)/(sqrt(30))`.

Discussion

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