question_answer

Angle between the vectors \[2\widehat{i}\,+6\widehat{j}+3\widehat{k}\] and\[12\widehat{i}\,+4\widehat{j}+3\widehat{k}\] is

A)  \[{{\cos }^{-1}}\left( \frac{1}{10} \right)\]    

B)  \[{{\cos }^{-1}}\left( \frac{9}{11} \right)\]     

C)   \[{{\cos }^{-1}}\left( \frac{9}{91} \right)\]

D)  \[{{\cos }^{-1}}\left( \frac{1}{9} \right)\]