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If the angle between the vectors A and B is θ, the value of the product (B × A) . A is equal to

1. BA² sinθ
2. BA² cosθ
3. BA² sinθ cosθ
4. zero

Correct answer: zero

Solution

The cross product B × A is perpendicular to both B and A. Since the dot product of two perpendicular vectors is zero, (B × A) . A equals zero.

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