$$W = \begin{pmatrix} 4 \\ 3 \end{pmatrix}$$ $$X = \begin{pmatrix} -3 \\ 4 \end{pmatrix}$$

$$\theta = 90^\circ$$ $$\cos(\theta) = 0$$ $$z = W \cdot X = 0$$

$W$

$X$

$\theta$