[tex]\it L>\ell\ de\ 3\ ori \Rightarrow\ L=3\ell\ \ \ \ \ \ (1)\\ \\ \\ \mathcal{P}=2\cdot(L+\ell) \stackrel{(1)}{\Longrightarrow} \mathcal{P}=2\cdot(3\ell+\ell) \Rightarrow \mathcal{P}=8\cdot\ell\ \ \ \ \ \ (2)\\ \\ \\ \mathcal{A}=L\cdot\ell \Rightarrow 60=L\cdot\ell\ \stackrel{(1)}{\Longrightarrow}\ 60=3\ell\cdot\ell \Rightarrow 3\ell^2=60|_{:3} \Rightarrow \ell^2=20 \Rightarrow \\ \\ \\ \Rightarrow \ell=\sqrt{20}=\sqrt{4\cdot5}=2\sqrt5\ \ \ \ \ \ (3)[/tex]
[tex]\it (2),\ (3) \Rightarrow \mathcal{P}=8\cdot2\sqrt5 \Rightarrow \mathcal{P}=16\sqrt5\ cm[/tex]
