Question

If straight line makes an angle ${\cos }^{-1}\left(\frac{1}{\sqrt{3}}\right)$ with each of the positive $x,y$ and $z-$axis, a vector parallel to that line is

• A. $\overline{i}$
• B. $\overline{i}+\overline{j}$
• C. $\overline{j}+\overline{k}$
• D. $\overline{i}+\overline{j}\overline{k}$

Answer 1

The correct option is A $\overline{i}$

We have,

D.C of line is $:\frac{1}{\sqrt{3}},\frac{1}{\sqrt{3}},\frac{1}{\sqrt{3}}$

Therefore,

Vector parallel to that line is $\overline{i}+\overline{j}+\overline{k}$ .

Then,

Option $A$ is correct answer.