A) \[\frac{\pi }{6}\]
B) \[\frac{\pi }{2}\]
C) \[\frac{\pi }{3}\]
D) \[\frac{\pi }{4}\]
Correct Answer: C
Solution :
\[\vec{c}=\hat{a}+2\hat{b}\] \[\vec{d}=5\hat{a}-4\hat{b}\] \[\vec{c}.\,\vec{d}=0\] \[\Rightarrow \,\,(\hat{a}+2\hat{b}).(5\hat{a}-4\hat{b})=0\] \[\Rightarrow 5+6\hat{a}.\,\hat{b}-8=0\] \[\Rightarrow \hat{a}.\,\hat{b}=\frac{1}{2}\] \[\Rightarrow \theta =\frac{\pi }{3}\]You need to login to perform this action.
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