Vectors Question 126

Question: The angle between the vectors $ \overrightarrow{A} $ and $ \overrightarrow{B} $ is $ \theta . $ The value of the triple product $ \overrightarrow{A},.,(\overrightarrow{B}\times \overrightarrow{A},) $ is

[CBSE PMT 1991, 2005]

Options:

A) $ A^{2}B $

B) Zero

C) $ A^{2}B\sin \theta $

D) $ A^{2}B\cos \theta $

Show Answer

Answer:

Correct Answer: B

Solution:

Let $ \overrightarrow{A},.(\overrightarrow{B},\times \overrightarrow{A})=\overrightarrow{A},.,\overrightarrow{C}, $ Here $ \overrightarrow{C}=\overrightarrow{B}\times \overrightarrow{A} $ Which is perpendicular to both vector $ \overrightarrow{A} $ and $ \overrightarrow{B} $ \ $ ,\overrightarrow{A},.\overrightarrow{,C}=0 $