[tex]\it \ell<L\ de\ 2\ ori \Rightarrow L>\ell\ de\ 2\ ori \Rightarrow L=2\ell\ \ \ \ (1)\\ \\ 2L+2\ell=300|_{:2} \Rightarrow L+\ell=150 \stackrel{(1)}{\Longrightarrow}\ 2\ell+\ell=150 \Rightarrow 3\ell=150|_{:3} \Rightarrow\\ \\ \Rightarrow \ell=50\ cm\ \ \ \ (2)\\ \\ \\ (1),(2)\Rightarrow L=2\cdot50 \Rightarrow L=100\ cm[/tex]
