\(-8+4i\\ r = \sqrt{(-8)^2+4^2} = \sqrt{80} \\ \alpha = tan^{-1}(\frac{4}{-8}) \Leftrightarrow \alpha =153^\circ 26' 5{,}8"\text{ of } \alpha = 333^\circ 26' 5{,}8"\\-8+4i\text{ ligt in kwadrant }2, \alpha \text{ ligt dus tussen }90^\circ \text{ en }180^\circ\\ \alpha = 153^\circ 26' 5{,}8"\)