Physics Two Dimensional Motion Question 136
Question: If $ A=5\widehat{i}+7\widehat{j}-3\widehat{k} $ and $ B=2\widehat{i}+2\widehat{j}-a\widehat{k} $ are perpendicular vectors, the value of a is:
Options:
A) $ -,2 $ B)8 C) $ -,7 $ D)$ -,8 $
Show Answer
Answer:
Correct Answer: D
Solution:
[d] $ \vec{A},\text{.},\vec{B},\text{=},\text{0} $
$ \text{or }( 5\hat{i}+7\hat{j}-3\hat{k} ).( 2\hat{i}+2\hat{j}-a\hat{k} )=0 $
$ \
Therefore 5\times 2+7\times 2+3a=0ora=-8 $
BETA
