Question

If `(vecaxxvecb)xx(vecbxxvecc)=vecb, where veca,vecb and vecc` are non zero vectors then (A) `veca,vecb and vecc can be coplanar (B) `veca,vecb and vecc` must be coplanar (C) `veca,vecb and vecc cannot be coplanar (D) none of these
A. `veca,vecb and vecv` can be coplanar
B. `veca, vecb and vecc` must be coplanar
C. `veca,vecb and vecc` cannot be coplanar
D. none of these

Answer 1

Correct Answer - c
`(veca xx vecb) xx (vecb xx vecc) = vecb`
` or [veca vecb vecc] vecb = vecb`
` or [veca vecb vecc] =1 `
therefore, `veca , vecb and vecc` cannot be coplanar.