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प्रश्न
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 ______
विकल्प
null vector
the unit vector along the line
any vector along the line
a vector perpendicular to the line
उत्तर
the unit vector along the line
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