If ` vec a` and vec b` are two non collinerar unit vectors and if `

1.	If ` vec a` and vec b` are two non collinerar unit vectors and if ` \| vec a+ vec b \| = sqrt 3`, then find the value of ` (vec a-vec b). (2 vec a+ vec b)`.
Answer» Given ` a= b= 1` and ` \| vec a + vec b\| = sqrt 2` :. ` a^2 +b^1+ 2 ab cos theta =3 ` or ` cos thete = 1//2` Now ( `vec a-vec b`). (` 2 vec a+vec b`)= `2 a^2 -b^2 - ab cos theta` = 2- 1 1/2 1/2` .

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If ` vec a` and vec b` are two non collinerar unit vectors and if ` | vec a+ vec b | = sqrt 3`, then find the value of ` (vec a-vec b). (2 vec a+ vec b)`.

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