JEE Main & Advanced
Mathematics
Vector Algebra
Question Bank
Critical Thinking
question_answer
If \[\mathbf{a}=\mathbf{i}+\mathbf{j}+\mathbf{k},\,\,\mathbf{a}\,.\,\mathbf{b}=1\] and \[\mathbf{a}\times \mathbf{b}=\mathbf{j}-\mathbf{k},\] then \[\mathbf{b}=\] [IIT Screening 2004]
A)\[\mathbf{i}\]
B)\[\mathbf{i}-\mathbf{j}+\mathbf{k}\]
C)\[2\mathbf{j}-\mathbf{k}\]
D)\[2\mathbf{i}\]
Correct Answer:
A
Solution :
Let \[\mathbf{b}={{b}_{1}}\,\mathbf{i}+{{b}_{2}}\,\mathbf{j}+{{b}_{3}}\mathbf{k}\]