AC-AB=AO+OC-(AO+OB)=OC-OB=-CO-OB=-(CO+OB)=-CB=BCvector
|BCvector|²=(pPitagora generalizat)=AC²+AB²-2AB * ACcos120°=
= (6√3)²+(6√3)²-2*(6√3)(6√3) *(-1/2)= (6√3)²(1+1+1)=(6√3)² *3⇒
⇒BC=(6√3) *√3=6*3=18 unitai lungime, ca nu ne-ai spus care anume
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