Question

Un tetraedru are toate muchile de 4 cm . Cum afli aria unei fete laterale?

Answer 1

$At = l^{2} \sqrt{3} =\ \textgreater \ Aria ~unei ~fete = \frac{ l^{2} \sqrt{3} }{4}$

=$\frac{16 \sqrt{3} }{4} = 4 \sqrt{3} cm^{2}$

Answer 2

Orice față a unui tetraetru este triunghi echilateral. 
$A_\triangle = \dfrac{l^2 \sqrt{3} }{4} \\ \\ A_\triangle = \dfrac{4^2 \sqrt{3} }{4} \\ \\ A_\triangle = \dfrac{16 \sqrt{3} }{4} \\ \\ \boxed{A_\triangle = 4 \sqrt{3} \ cm^2 }$