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What is the angle which the vector `(hat(i)+hat(j)+sqrt(2)hat(k))` makes with the z-axis ?A. `(pi)/(4)`B. `(pi)/(3)`C. `(pi)/(6)`D. `(2pi)/(3)`

Answer» Correct Answer - A
`vec(a)=(hat(i)+hat(j)+sqrt(2)hat(k))rArr|vec(a)|=sqrt(1^(2)+1^(2)+(sqrt(2))^(2))=sqrt(4)=2`.
Direction ratios of `vec(a)` are 1, 1, `sqrt(2)`.
Direction cosines of `vec(a)` are `(1)/(2), (1)/(2), (sqrt(2))/(2), i.e., (1)/(2), (1)/(2), (1)/(sqrt(2))`.
`:. cos lambda=(1)/(sqrt(2))rArr lambda=(pi)/(4)`.


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