It is found that `|A+B|=|A|`,This necessarily implies.

Options

A. `vecB=0`
B. `vecA,vecB` are antiparallel
C. `vecA,vecB` are perpendicular
D. `vecA,vecB le0`.

Answer

A, B

Explanation

Given that `|A+B|=|A|` or `|A+B|^(2)=|A|^(2)`
`=|A|^(2)+|B|^(2)+|A||B|cos theta=|A|^(2)`
Where `theta` is angle between `A` and `B`.
`=|B|=0` or `|B|+2|A|cos theta=0`
`=cos theta =-|B|/(2|A|)`
If `A` and `B` are antiparallel, then `theta=180^(@)`
Hence, from Eq (i)
`-1=-|B|/(2|A|)rArr|B|=2|A|`