Răspuns:
P = 18 cm
Explicație pas cu pas:
[tex]\displaystyle\bf\\P_{\Delta \:echilateral}=3l[/tex]
[tex]\displaystyle\bf\\h_{\Delta\: echilateral}=\frac{l\sqrt{3}}{2}[/tex]
[tex]\displaystyle\bf\\3\sqrt{3}=\frac{l\sqrt{3}}{2}\implies l=\frac{3\sqrt{3}*2}{\sqrt{3}}[/tex]
[tex]\displaystyle\bf\\h=\frac{6\sqrt{3}}{\sqrt{3}}[/tex]
[tex]\displaystyle\bf\\h=\frac{18}{3}=6\:cm[/tex]
[tex]\displaystyle\bf\\P_{\Delta}=3*6[/tex]
[tex]\displaystyle\bf\\P_{\Delta}=18\:cm[/tex]
