Question

Select the correct option from the given alternatives:

If l, m, n are direction cosines of a line then `"l"hat
"i" + "m"hat"j" + "n"hat"k"` is ______ 

Options

• null vector

• the unit vector along the line

• any vector along the line

• a vector perpendicular to the line

Answer 1

the unit vector along the line