The rectangular components of a vector lying in xy plane are (n+1) and 1. If coordinate system is turned by 60o , they are n & 3 respectively the value of ‘n’
Rotation of co-ordinate system does not change the vector.
Hence
⇒ n2+2n+1+1 = n2 +9
⇒ 2n = 7 ⇒ n = 3.5