[tex]\displaystyle Se~aplica~\underline{teorema~lui~Menelaus}~in~triunghiul:~ \Delta ADC~cu \\ \\ transversala~ B-F-E:~ \frac{BC}{BD} \cdot \frac{FD}{FA} \cdot \frac{EA}{EC}=1 \Leftrightarrow \\ \\ \Leftrightarrow2 \cdot \frac{FD}{FA} \cdot \frac{EA}{EC} =1 \Rightarrow \boxed{AF \cdot EC=2AE \cdot FD}. [/tex]
