Notăm lungimile laturilo cu x, y, z.
[tex]\it x+y+z=180\ \ \ \ (1)\\ \\ \\ \{x,\ \ y,\ \ z\}\ d.\ p.\ \{3,\ \ 4,\ \ 5\} \Rightarrow \dfrac{x}{3}=\dfrac{y}{4}=\dfrac{z}{5}=\dfrac{x+y+z}{3+4+5}\ \stackrel{(*)}{=}\ \dfrac{180}{12}=15\Rightarrow\\ \\ \\ \Rightarrow \begin{cases} \it x=3\cdot15=45\ cm\\ \\ \it y=4\cdot15=60\ cm\\ \\ \it z=5\cdot15=75\ cm\end{cases}[/tex]
