a)
Comparăm ΔABC cu ΔAFE.
[tex]\it \left.\begin{aligned}\hat A\ -\ unghi\ comun\\ \\ \it \dfrac{AB}{AF}=\dfrac{100}{20}=5\\ \\ \\ \it\dfrac{AC}{AE}=\dfrac{60}{12}=5\end{aligned}\right\}\ \stackrel{LUL}{\Longrightarrow}\ \Delta ABC\ \sim\ \Delta AFE \Rightarrow \dfrac{BC}{EF}=\dfrac{AB}{AF}=5 \Rightarrow\\ \\ \\ \Rightarrow \dfrac{BC}{16}=5 \Rightarrow BC=16\cdot5=80\ cm[/tex]
[tex]\it FC=AC-AF=60-20=40\ cm\\ \\ BE=AB-AE=100-12=88\ cm\\ \\ \mathcal{P}_{BEFC}=BE+EF+FC+BC=88+16+40+80=224\ cm[/tex]
