[tex]\it Din\ \Delta ABC \Rightarrow MN||AB\ \stackrel{T.Thales}{\Longrightarrow}\ \dfrac{CM}{MB}=\dfrac{CN}{NA}\ \ \ \ \ (1)\\ \\ \\ Din\ \Delta ACD \Rightarrow NP||AD\ \stackrel{T.Thales}{\Longrightarrow}\ \dfrac{CN}{NA}=\dfrac{CP}{PD}\ \ \ \ \ (2)\\ \\ \\ (1),\ (2) \Rightarrow \dfrac{CM}{MB}=\dfrac{CP}{PD}\ \ \ \ \ (3)[/tex]
Din relația (3), cu reciproca teoremei lui Thales în ΔBCD, ⇒MP || BD .
