A) \[\frac{\pi }{4}\]
B) \[\frac{\pi }{3}\]
C) \[\frac{\pi }{2}\]
D) \[\pi \]
Correct Answer: D
Solution :
\[\overrightarrow{AB}=\mathbf{i}+4\mathbf{j}-\mathbf{k},\] \[\overrightarrow{CD}=-2\mathbf{i}-8\mathbf{j}+2\mathbf{k}\] \[\cos \theta =\frac{\overrightarrow{AB}.\overrightarrow{CD}}{|\overrightarrow{AB}|.|\overrightarrow{CD}|}=\frac{-2-32-2}{\sqrt{18}.\sqrt{72}}\] \[=\frac{-2-32-2}{2\times 18}=-1\Rightarrow \theta =\pi .\]You need to login to perform this action.
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