a. notam AOB=x BOC=x+10 COD=2(x+10) DOA=2(x+10)/2-10=x+10-10=x x+x+10+2(x+10)+x=360 5x+30=360 5x=330, x=66 AOB=66 BOC=66+10=76 COD=2BOC=152 DOA=COD/2-10=66 b. deoarece AOB=66, DOA=66 AOB=DOA, deci OA bisectoare (imparte unghiul BOD in doua parti egale)