Vector v is (4√3,√3).

Find the angle between v and i.

Use the dot product

(4√3,√3)⋅(1,0) = |(4√3,√3)||(1,0)|cosØ , where Ø is the angle between them
4√3 + 0 = √51√1cosØ
cosØ = 4√3/√51
Ø = appr. 14.04°