$$ \overline{CF} = 5e \cdot sin(45°) = \frac{5e}{\sqrt{2}}$$
$$ \overline{FM} = \frac{ \overline{CF}}{2} = \frac{5e}{2 \sqrt{2}} \ .$$
Sei Beta der Winkel bei A im Dreieck AMF:
$$ \beta = 180° - 60° - 90° = 30°$$
$$ \Rightarrow \quad \overline{AM} = \frac{ \overline{FM}}{sin( \beta )} = \frac{5e}{\sqrt{2}}$$
$$ \Rightarrow \quad \overline{AF} = \overline{AM} \cdot cos( \beta ) = \frac{5e \sqrt{3}}{2 \sqrt{2}} $$
$$ tan( \epsilon ) = \frac{ \overline{CF}}{ \overline{AF}} = \frac{5e}{\sqrt{2}} \cdot \frac{2 \sqrt{2}}{5e \sqrt{3}} = \frac{2}{ \sqrt{3}} = \frac{2}{3} \cdot \sqrt{3} \ .$$