Vector Algebra Question 155
Question: What should be added in vector $ \mathbf{a}=3\mathbf{i}+4\mathbf{j}-2\mathbf{k} $ to get its resultant a unit vector i
[Roorkee 1977]
Options:
A) $ -,2\mathbf{i}-4\mathbf{j}+2\mathbf{k} $
B) $ -2\mathbf{i}+4\mathbf{j}-2\mathbf{k} $
C) $ 2\mathbf{i}+4\mathbf{j}-2\mathbf{k} $
D) None of these
Show Answer
Answer:
Correct Answer: A
Solution:
- Let $ \mathbf{b} $ should be added, then $ \mathbf{a}+\mathbf{b}=\mathbf{i} $
$ \Rightarrow \mathbf{b}=\mathbf{i}-\mathbf{a}=\mathbf{i}-(3\mathbf{i}+4\mathbf{j}-2\mathbf{k})=-2\mathbf{i}-4\mathbf{j}+2\mathbf{k}. $
BETA
