Winkel zwischen zwei Vektoren
$$\gamma = \arccos \left( \frac{\overrightarrow a \cdot \overrightarrow b}{\left| \overrightarrow a \right| \cdot \left| \overrightarrow b \right|} \right)$$
ε = ARCCOS( [-2, 2]·[6, 2] / (|[-2, 2]|·|[6, 2]|) ) = 116.57°
φ = ARCCOS( [2, -2]·[6, 2] / (|[2, -2]|·|[6, 2]|) ) = 63.43°