Răspuns:
41
Explicație pas cu pas:
[tex]\left.\begin{cases}P _{\bigtriangleup} = 123\,\,\text{cm}\\P _{\bigtriangleup} = 3l\\ \end{array}\right|\Rightarrow 3l = 123\,\,\text{cm} \Rightarrow l = \dfrac{123}{3}\,\,\text{cm} \Rightarrow \\\\ \\ \Rightarrow\,\boxed{l = 41\,\,\text{cm}}[/tex]
