∡AOB= ∡BOC *2
∡AOB= ∡AOC-40 rezulta ∡AOC= ∡AOB+40 = 2*∡BOC+40
∡AOB+∡BOC + ∡AOC= 360 grade (suma masurilor ∡in jurul unui punct)
inlocuind rezulta
∡BOC *2+ ∡BOC +2*∡BOC+40=360
5* ∡ BOC= 360-40 ⇒ 5*∡BOC= 320 ⇒ ∡BOC= 320:5= 64 grade
∡AOB= 64*2= 128 grade
∡AOC= 128+40= 168 grade