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Question 7: If the angle between vectors A and B is $\theta$, then the value of the product $(B\times A).A$ is equal to
ABA² cos θ
BBA² sin θ
Czero
DBA² sin θ cos θ
Answer & Solution
Correct answer: C. zero
B×A will be perpendicular to both A and B.
$$
(B \times A).A = (B \times A)A \cos \theta \text{ (here } \theta = 90^\circ\text{)}
$$
$$
= |B \times A| |A| \cos 90
$$
$$
= 0
$$
Hence option c is the answer.
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