Question

If `vecA=lamda(vecuxxvecv)+mu(vecvxxvecw)+v(vecwxxvecu) and [vecu vecv vecw]=1/5 then lamda +mu+v=` (A) 5 (B) 10 (C) 15 (D) none of these

Answer 1

Correct Answer - 6
q= Area of parallelogram with `vec(OA) and vec(OC)` as adjacent sides
`|vec(OA) xx vec(OC)|`
`|veca xx vecb|`
p = Area of quadrilateral OABC
`1/2|vec(OA)xx vec(OB)|+1/2|vec(OB)xx vec(OC)|`
`1/2[|veca xx(10 veca + 2vecb)|+|(10veca + 2vecb)xxvecb|]`
`1/2|(12veca xx vecb)|=6|veca xx vecb| Rightarrow k =6`