a)
[tex][MA]\equiv[NB] \\ \\ \angle MAB\equiv\angle NBA \\ \\ [AB]\equiv[BA] \\ \\ \Rightarrow\triangle MAB\equiv\triangle NBA,~caz~LUL \\ \\ \Rightarrow[MB]\equiv[NA][/tex]
b)
[tex][MA]\equiv[NB] \\ \\ [AN]\equiv[BM] \\ \\ [NM]\equiv[MN] \\ \\ \Rightarrow\triangle MAN\equiv\triangle NBM,~caz~LLL[/tex]
