x+3x=180° ⇒4x=180⇒ x=45°⇒∡COB=45°
∡BOD=3x=3·45°=135°
∡AOD=∡BOC( ca ∡ opuse la varf)⇒∡AOD=45°
∡DOF=∡AOF=∡AOD/2⇒∡DOF=∡∡AOF=45/2=22°30' (OF fiind bisectoarea ∡AOD)
∡AOC=∡DOB(ca ∡ opuse la varf)⇒ ∡AOC=∡DOB=135°
OM este bisectoarea lui ∡AOC ⇒∡AOM=∡MOC=∡AOC/2=135/2=67°30'