VITEEE 2014 Paper

p, q and r are reciprocal vectors of a, b and c respectively.
So 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
(la + mb + nc). (Ip + mq + nr)
= I2+m2+n2