JEE MainMathematicsVector AlgebraMCQ+4 / −1
If and are unit vectors and is the acute angle between them, then is a unit vector for :
- Ano value of
- Bexactly one value of
- Cexactly two values of
- Dmore than two values of
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Correct answer: B
- Let us simplify the given vector:
We are given that and are unit vectors, and the angle between them is .
- Use the magnitude formula for cross product:
Since both are unit vectors,
so,
Therefore,
- For to be a unit vector, its magnitude must be :
- Now is acute, so
In the acute interval, is strictly increasing, so the equation
has exactly one solution.
- Hence, there is exactly one value of .
Therefore, the correct option is:
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