Vector Algebra Question 253

Question: If C is the middle point of AB and P is any point outside AB, then

[MNR 1991; UPSEAT 2000; AIEEE 2005]

Options:

A) $ \overrightarrow{PA}+\overrightarrow{PB}=\overrightarrow{PC} $

B) $ \overrightarrow{PA}+\overrightarrow{PB}=2,\overrightarrow{PC} $

C) $ \overrightarrow{PA}+\overrightarrow{PB}+\overrightarrow{PC}=0 $

D) $ \overrightarrow{PA}+\overrightarrow{PB}+2,\overrightarrow{PC}=0 $

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Answer:

Correct Answer: B

Solution:

  • $ \overrightarrow{PA}+\overrightarrow{PB}=(\overrightarrow{PA}+\overrightarrow{AC})+(\overrightarrow{PB}+\overrightarrow{BC})-(\overrightarrow{AC}+\overrightarrow{BC}) $ = $ \overrightarrow{PC}+\overrightarrow{PC}-(\overrightarrow{AC}-\overrightarrow{CB})=2\overrightarrow{PC}-0, $ $ (\because ,\overrightarrow{AC}=\overrightarrow{CB}) $
    $ \therefore $ $ \overrightarrow{PA}+\overrightarrow{PB}=2\overrightarrow{PC} $ .