If `overset(to)(a) , overset(to)(b) , overset(to)(c ) ` are non-coplanar unit vectors such that `overset(to)(a) xx (overset(to)(b) xx overset(to)(c )) = ((overset(to)(b) + overset(to)(c )))/(sqrt(2))`, then the angle between `overset(to)(a) " and " overset(to)(b)` isA. `(3pi)/(4)`B. ` (pi)/(4)`C. `(pi)/(2)`D. `pi`

If `overset(to)(a) , overset(to)(b) , overset(to)(c ) ` are non-coplan

1.	If `overset(to)(a) , overset(to)(b) , overset(to)(c ) ` are non-coplanar unit vectors such that `overset(to)(a) xx (overset(to)(b) xx overset(to)(c )) = ((overset(to)(b) + overset(to)(c )))/(sqrt(2))`, then the angle between `overset(to)(a) " and " overset(to)(b)` isA. `(3pi)/(4)`B. ` (pi)/(4)`C. `(pi)/(2)`D. `pi`
Answer» Correct Answer - A Since `vec(a) xx (vec(b) xx vec(c )) = (vec(b) + vec(c ))/(sqrt(2))` ` rArr (vec(a) " ." vec(c )) vec(b) - (vec(a) ". " vec(b)) vec(c ) = (1)/(sqrt(2)) vec(b) + (1)/(sqrt(2)) vec( c)` On equating the coefficient of `vec(c )` we get `rArr \|vec(a)\|\|vec(b)\|\| cos 0 = (1)/(sqrt(2))` ` :. cos 0 = (1)/(sqrt(2)) rArr 0= (3pi)/(4)`

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