A) \[\frac{5}{14}\]
B) \[\frac{1}{7}\]
C) \[\frac{3}{14}\]
D) \[\frac{1}{14}\]
Correct Answer: D
Solution :
\[\overset{\to }{\mathop{a}}\,\,\cdot \overset{\to }{\mathop{b}}\,=ab\cos \theta \] \[\therefore \]\[(2\hat{i}-3\hat{j}+\hat{k})\cdot (3\hat{i}+\hat{j}-2\hat{k})=ab\cos \theta \] \[\Rightarrow \] \[6-3-2=\sqrt{(4+9+1)\,(9+1+4)}\cos \theta \] \[\Rightarrow \] \[1=\sqrt{14\times 14}\cos \theta \] \[\Rightarrow \] \[1=14\cos \theta \] \[\Rightarrow \] \[\cos \theta =\frac{1}{14}\]You need to login to perform this action.
You will be redirected in
3 sec