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) \[{{\cos }^{-1}}\left( \frac{1}{9} \right)\]
Correct Answer: C
Solution :
\[\theta ={{\cos }^{-1}}\left( \frac{2\times 12+6\times (-4)+3(3)}{\sqrt{{{2}^{2}}+{{6}^{2}}+{{3}^{2}}}\sqrt{{{12}^{2}}+{{4}^{2}}+{{3}^{2}}}} \right)\] \[={{\cos }^{-1}}\left( \frac{9}{7\times 13} \right)={{\cos }^{-1}}\left( \frac{9}{91} \right)\]You need to login to perform this action.
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