Vector Algebra Question 379
Question: If $ \mathbf{a}\ne \mathbf{0},\mathbf{b}\ne \mathbf{0} $ and $ |\mathbf{a}+\mathbf{b}|,=,|\mathbf{a}-\mathbf{b}|, $ then the vectors a and b are
[Roorkee 1986; MNR 1988; IIT Screening 1989; MP PET 1990, 97; RPET 1984, 90, 96, 99; KCET 1999]
Options:
A) Parallel to each other
B) Perpendicular to each other
C) Inclined at an angle of $ 60^{o} $
D) Neither perpendicular nor parallel
Show Answer
Answer:
Correct Answer: B
Solution:
- $ |\mathbf{a}+\mathbf{b}|=|\mathbf{a}-\mathbf{b}| $ ; Squaring both sides, we get $ 4\mathbf{a}.\mathbf{b}=0 $
$ \Rightarrow \mathbf{a} $ is perpendicular to $ \mathbf{b}. $
BETA
