MathNet 2024-part-05 — 168 problems (EN–VI) Question 24

Let $ABCD$ be a parallelogram and the points $E$, $F$ are in the exterior. If triangles $BCF$ and $DEC$ are similar, i.e., $\triangle BCF \sim \triangle DEC$, prove that triangle $AEF$ is similar to these two triangles.