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Let a vector bar(r) make angle 60^(@), 3...

Let a vector `bar(r)` make angle `60^(@), 30^(@)` with x and y-axes respectively.
What are the direction cosines of `bar(r)` ?

A

`(:1/2,(sqrt(3))/(2),0:)`

B

`(:1/2,(sqrt(3))/(2),0:)`

C

`(:(1)/(sqrt(2)),(1)/(sqrt(2)),0:)`

D

`(:-(1)/(2),(sqrt(3))/(2),0:)`

Text Solution

Verified by Experts

The correct Answer is:
A
`r = lt 1, m, n gt , r = lt cos 60^(@), cos 30^(@), cos90^(@) gt`
Direction cosines of `vec(r)= lt (1)/(2) , (sqrt(3))/(2) , 0 lt`
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