A) l + m + n
B) \[{{l}^{3}}+{{m}^{3}}+{{n}^{3}}\]
C) \[{{l}^{2}}+{{m}^{2}}+{{n}^{2}}\]
D) None of these
Correct Answer: C
Solution :
\[\because \] p, q and r are reciprocal vectors of a, b and c respectively. \[\therefore \] p. r = 1 p . b = 0 p . c q . a = 0, q . b = 1, q . c = 0 r.a = 0, r.b = 0, r . c = 1 \[\therefore \] (la + mb + nc) . (lp + mq + nr) = \[{{l}^{2}}+{{m}^{2}}+{{n}^{2}}\]
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