[tex]\ \textless \ A = 120^o \\
=\ \textgreater \ ~\ \textless \ C=~\ \textless \ A = 120^o~~~~~(fiind ~~unghiuri ~~opuse) \\
=\ \textgreater \ ~ \ \textless \ B = \ \textless \ D = 180-120=60^o ~(fiin ~suplementarele ~lui~A~si~B ) \\
\text{Deoarece unghiurile ascutite sunt de } 60^o, \text{diagonala mica imparte } \\
\text{in doua triunghiuri echilaterale. } \\
=\ \textgreater \ Latura = diagonala ~mica = 6\;cm \\
=\ \textgreater \ P = 4 \times 6 = 24 cm [/tex]
