Răspuns :
[tex]\displaystyle\bf\\A=81~cm^2\\\\A=L^2\\\\\implies~L=\sqrt{A}=\sqrt{81}=9~cm\\\\P=4\times L=4\times 9=\boxed{\bf36~cm}[/tex]
[tex]\displaystyle\bf\\A=81~cm^2\\\\A=L^2\\\\\implies~L=\sqrt{A}=\sqrt{81}=9~cm\\\\P=4\times L=4\times 9=\boxed{\bf36~cm}[/tex]