Salut!
A triunghi ABC = AB x AC X sinA / 2 = 6 x sin(π/8);
In cazul de fata folosim formula de trigonometrie sin(x/2) = [tex] \sqrt{ \frac{1-cosx}{2}} ;[/tex] => sin(π/8) = [tex] \frac{ \sqrt{2- \sqrt{2}}}{2} [/tex];
La final, Aria triunghi ABC = 3[tex] \sqrt{2- \sqrt{2}} .[/tex]
Bafta!