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Question
If `veca` and `vecb` are unit vectors, then what is the angle between `veca` and `vecb` for `sqrt(3) veca - vecb` to be a unit vector?
Options
30°
45°
60°
90°
Solution
30°
Explanation:
We have `(sqrt(3) veca - vecb)^2 = 3veca^2 + vecb^2 - 2sqrt(3) veca*vecb`
`\implies veca * vecb = sqrt(3)/2`
`\implies` cos θ = `sqrt(3)/2`
`\implies` θ = 30°
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