Aria unui triunghi echilateral se calculeaza cu formula:
[tex]A_3=\frac{l^2\sqrt{3}}{4}[/tex]
Inlocuind aria cu 25 radical din 3 obtinem:
[tex]\frac{l^2\sqrt{3}}{4}=25\sqrt{3}=\ \textgreater \ l^2\sqrt{3}=100\sqrt{3}|:\sqrt{3}=\ \textgreater \ l^2=100 =\ \textgreater \ l = 10 [/tex]
Tetraedrul are 6 muchii, deci suma muchiilor este:
[tex]S_m=6*l=\ \textgreater \ S_m=6*10=\ \textgreater \ S_m=60[/tex]
