question_answer

If \[\mathbf{a}=\mathbf{i}+2\mathbf{j}+3\mathbf{k},\,\,\,\mathbf{b}=-\mathbf{i}+2\mathbf{j}+\mathbf{k}\] and \[\mathbf{c}=3\mathbf{i}+\mathbf{j},\] then the unit vector along its resultant is      [Roorkee 1980]

A) \[3\mathbf{i}+5\mathbf{j}+4\mathbf{k}\]      

B) \[\frac{3\mathbf{i}+5\mathbf{j}+4\mathbf{k}}{50}\]

C) \[\frac{3\mathbf{i}+5\mathbf{j}+4\mathbf{k}}{5\sqrt{2}}\]       

D) None of these