\(-2+3i\\ r = \sqrt{(-2)^2+3^2} = \sqrt{13} \\ \alpha = tan^{-1}(\frac{3}{-2}) \Leftrightarrow \alpha =123^\circ 41' 24{,}2"\text{ of } \alpha = 303^\circ 41' 24{,}2"\\-2+3i\text{ ligt in kwadrant }2, \alpha \text{ ligt dus tussen }90^\circ \text{ en }180^\circ\\ \alpha = 123^\circ 41' 24{,}2"\)