Decompose the vector into vectors which are parallel and perpendicular to the vector
let and
let where u is vector parallel to b and v is vector perpendicular to b
So, ; where p is some constant
Substituting this value in above equation
Now according to conditions since vector v and b are perpendicular to each other
6 – p – 3 – p – 6 – p = 0
P = –1
So,
Substituting this value of in above equation