figura 1 )
∡ABC = ∡AOC/2 = 110°/2 = 55°
∡ABO = ∡BAO ∡CBO = ∡BCO = 55°/2 = 27°30'
∡AOB = ∡COB = 180° - 55° = 125°
figura 2)
∡DOF = (DF) = 70°
∡DEF = ∡DOF/2 = 70°/2 = 35°
∡EDO = ∡DEO = ∡FEO = ∡EFO = 35°/2 = 17°30'
∡DOE = ∡FOE = 180° - 35° = 145°
figura 3)
∡HGI = (HI)/2 = 40°/2 = 20°
