Aria triung. in functe de coordonate:
-fie x1,x2,y1,y2,z1,z2 coordonatele unui triunghi
-a(lungimea unei laturi)=sqrt(abs((x1-y1)*(x2-y2)))
-b(lungimea unei laturi)=sqrt(abs((x1-z1)*(x2-z2)))
-c(lungimea unei laturi)=sqrt(abs((y1-z1)*(y2-z2)))
p=(a+b+c)/2

A-triunghi=sqrt(p*(p-a)*(p-b)*(p-c)) - Heron => formula cu coordonate
A-poligon = ( suma 1->N ) x[i]*y[i+1]-x[i+1]*y[i]
A-triunghi=1/4*sqrt( 4*a^2*b^2 - (a^2+b^2-c^2)^2 )
