a)semiperimetrul p=(AB+BC+AC)/2
Aria S=radical(p(p-AB)(p-BC)(p-AC))
p=(5+7+8)/2=10 cm, S=radical(10*(10-5)*(10-7)*(10-8))=radical(10*5*3*2)= =radical(300)=10*radical(3) cmp
b) Triunghi echilateral S=(radical(3)*latura^2)/2=18*radical(3) cmp
c) Triunghiul ABC dreptunghic, AB si BC catete, S=AB*BC/2=2*3*2/2=6cmp