A) \[1,4,3\]
B) \[1/\sqrt{26},\,\,4/\sqrt{26},\,\,3/\sqrt{26}\]
C) \[-1/\sqrt{26},\,\,4/\sqrt{26},\,\,3/\sqrt{26}\]
D) \[1/\sqrt{26},-\,\,4/\sqrt{26},\,\,3/\sqrt{26}\]
Correct Answer: B
Solution :
Let \[\vec{a}=\hat{i}+4\hat{j}+3\hat{k}\] \[|\vec{a}|=\sqrt{1+16+9}=\sqrt{26}\] \[\therefore \] \[\vec{a}=\frac{{\vec{a}}}{|\vec{a}|}=\frac{\hat{i}+4\hat{j}+3\hat{k}}{\sqrt{26}}\] \[\therefore \] Direction cosine \[=\frac{1}{\sqrt{26}},\frac{4}{\sqrt{26}},\frac{3}{\sqrt{26}}\]
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