Find the angle θ between the vectors \(\vec a = \;\hat i + \;\hat j + \;\hat k\) and \(\vec b = \;\hat i - \;\hat j - \;\hat k\) ?
1
\({\cos ^{ - 1}}\left( { - \frac{1}{5}} \right)\)
2
\({\cos ^{ - 1}}\left( { - \frac{1}{4}} \right)\)
3
\({\cos ^{ - 1}}\left( { - \frac{1}{3}} \right)\)
4
\({\cos ^{ - 1}}\left( { \frac{1}{3}} \right)\)
5
Question Not Attempted