Se considera figura 9. Stiind ca TRIUNGHIU ABC este un triunghi isoscel cu baza BC , AN congruent AM SI UNGHIUL NAB congruent cu UNGHIUL MAC , demonstrati ca BN congruent MC PLS DAU COROANA

Răspuns:
[tex]\left.\begin{matrix} AB \equiv AC \\ AN \equiv AM \\ \measuredangle NAB \equiv \measuredangle MAC \end{matrix}\right\} \xrightarrow[L.U.L.]{criteriul} \Delta ABN \equiv \Delta ACM[/tex]
[tex]\Rightarrow \boldsymbol{BN \equiv MC}\\[/tex]