MathNet 2022-part-02 — 197 problems (EN–VI) Question 46

Points $A$, $D$, $E$ and $C$ lie on a line in this order. Point $B$ is chosen such that triangles $ADB$ and $BEC$ are similar (in this specific order of vertices), moreover $EC = 2AD$ and $\angle ABC = 120^\circ$. Find $\frac{AC}{AD}$.