Question

Se considera triunghiul ABC, cu AB=AC=10 si BC=12. Aratati ca sin B=4/5

Answer 1

triunghiul ABC, cu AB=AC=10 si BC=12
ducem AD inaltimea pe BC
BD=DC=12/2=6 
AD=√(10²-6²)=√(100-36)=√64=8
sin B=AD/AB=8/10=4/5

Answer 2

ABC isoscel, baza BC
Fie AD⊥BC,D∈BC⇒BD=12:2=6
AD=(pitagora) =√(AB²-AD²)=√(10²-6²)=8
sin ∡B=cateta opusa /ipotenuza=AD/AB=8/10=4/5, C.C.T.D.