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If `veca, vecb, vecc` are non coplanar vectors and `vecp, vecq, vecr` are reciprocal vectors, then `(lveca+mvecb+nvecc).(lvecp+mvecq+nvecr)` is equal toA. `l^(2)+m^(2)+n^(2)`B. lm+mn+nlC. 0D. None of these

Answer» Correct Answer - A
The vectors reciprocal to `veca,vecb,vecc`, are given by `vecp=(vecb xx vecc)/[vecavecbvecc], vecq= (vecc xx veca)/[vecavecbvecc], vecr = (veca xx vecb)/([vecavecbvecc])`such that `veca.vecp=1, veca.vecq=veca.vecr=0`,
`vecb.vecq=1, vecb.vecp=vecb.vecr=0`
`vecc.vecr=1, vecc. vecp=vecc.vecq=0`
This gives `(lveca+mvecb+nvecc).(lvecp+mvecq+nvecr)`
`=l^(2)+m^(2)+n^(2)`.


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