vector `vecc` are perpendicular to vectors `veca= (2,-3,1) and vecb= (1, -2,3) ` and satifies the condition `vecc. (hati + 2hatj - 7 hatk) = 10` then vector `vecc` is equal to
`(a) (7,5,1)` `(b) (-7,-5,-1)` `(c) (1,1,-1)` `(d)` none of these

Options

A. 7,5,1
B. (-7, -5, -1)
C. 1,1,-1
D. none of these

Answer

a

Explanation

Let `vecc = lambda (veca xx vecb)`.
Hence, ` lambda(veca xx vecb) . (hati + 2hatj -7hatk) =10`
` Rightarrow lambda|{:(2,-3,1),(1,-2,3), (1,2,-7):}|=10`
`or lambda = -1`
` Rightarrow vecc = - (veca xx vecb)` \