vector

I assume that you're trying to generate a unit vector

If so.....let  u  =  < a, b >

The unit  vector is given by :

<    a / √[a^2 + b^2] ,  b / √{ a^2 + b^2 ]  >

how do i plug in the unit vector?

Each unit vector has the length 1

$\text{2D unit vector } \vec{v}_0 = \frac{\vec{v}}{v} \qquad \text{ with } \qquad \vec{v} = \binom {v_x}{v_y} \qquad \text{ and} \qquad v = \sqrt{v_x^2+v_y^2}$

$\text{3D unit vector } \vec{v}_0 = \frac{\vec{v}}{v} \qquad \text{ with } \qquad \vec{v} = \begin{pmatrix} v_x \\ v_y \\ v_z \end{pmatrix} \qquad \text{ and} \qquad v = \sqrt{v_x^2+v_y^2+v_z^2}$