[tex]\it Vom\ compara\ \Delta ACM\ \c{s}i\ \Delta ABC:\\ \\ \hat A= unghi\ comun\ \ \ \ \ (1)\\ \\ \widehat{MCA} \equiv\ \hat B\ \ \ \ \ (2)\\ \\ (1),\ (2) \ \stackrel{(U.U.)}{\Longrightarrow}\ \Delta ABC \sim \Delta ACM \Rightarrow \dfrac{BC}{CM}=\dfrac{AC}{AM} \Rightarrow \dfrac{18}{CM}=\dfrac{12}{6} \Rightarrow \\ \\ \\ \Rightarrow \dfrac{18}{CM}=2 \Rightarrow CM=9\ cm[/tex]
