A) \[P+Q\]
B) \[Q\]
C) \[P\]
D) \[\frac{P+Q}{2}\]
E) \[P-Q\]
Correct Answer: B
Solution :
In first case \[R=\sqrt{{{P}^{2}}+{{Q}^{2}}+2PQ\cos \theta }\] ...(i) where\[\theta \]is the angle between P and Q. In second case, \[(\overrightarrow{P}+2\overrightarrow{Q}).\overrightarrow{P}=0\] or \[\overrightarrow{P}\overrightarrow{P}+2(\overrightarrow{Q}.\overrightarrow{P})=0\] or \[{{P}^{2}}+0=0\] or \[P=0\] Putting\[P=0\]in Eq. (i), we get \[R=\sqrt{0+{{Q}^{2}}+0}=Q\]You need to login to perform this action.
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