What is the cosine of the angle which the vector `sqrt(2) hat i+ hat j+ hat k`makes with y-axis?

What is the cosine of the angle which the vector `sqrt(2) hat i+ hat j

1.	What is the cosine of the angle which the vector `sqrt(2) hat i+ hat j+ hat k`makes with y-axis?
Answer» The given vector is `veca = (sqrt(2) hati + hatj + hatk)` . Direction ratios of `veca` are `sqrt(2),1,1`. `\|veca\|= sqrt((-2)^(2) + 1^(2) + 1^(2)) = sqrt(4) = 2` `:.` direction cosines of `veca` are `(sqrt(2))/(2), 1/2,1/2` Let `veca` make angle `beta` with the y-axis. Then, clearly, `cos beta = 1/2`.

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