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Angle between vectors ` veca and vecb " where " veca,vecb and vecc` are unit vectors satisfying ` veca + vecb + sqrt3 vecc = vec0` isA. ` pi/6`B. `pi/4`C. `pi/3`D. ` pi/2`

Answer» Correct Answer - C
we have,
` veca + vecb + sqrt3 vecc = vec0`
` Rightarrow veca | vecb = sqrt3 vecc`
` Rightarrow |veca + vecb| = sqrt3 |vecc|`
` Rightarrow |veca + vecb|^(2) =3 |vecc|^(2) `
` Rightarrow |veca|^(2) +|vecb|^(2) + 2|veca||vecb| cos theta =3 |veca|^(2) `
where ` theta ` is the angle between ` veca and vecb` .
` Rightarrow 1 +1 + 2 cos theta =3 Rightarrow = 1/2 Rightarrow theta = pi/3`


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