[tex]\it Fie\ x-lungimea\ fiec\breve arei\ catete \Rightarrow ipotenuza=x\sqrt2\\ \\ \mathcal{A}=\dfrac{c_1\cdot c_2}{2}=\dfrac{x\cdot x}{2}=18 \Rightarrow x\cdot x=2\cdot18 \Rightarrow x\cdot x=36=6\cdot6 \Rightarrow x=6\\ \\ \mathcal{P}=6+6+6\sqrt2=12+6\sqrt2\ cm[/tex]
