Daca m(∡AOB)=120° =>m(∡AOM)=m(∡MOB)=60°
Daca m(∡AOB)=120° =>m(∡BOC)=60° (ipoteza, unghiuri suplementare)
=>m(∡MOC)=60+60=120°
Daca m(∡BOC)=70° =>m(∡AOB)=110° =>m(∡AOM)=m(∡MOB)=55°
=>m(∡MOC)=55+70=125°
Daca m(∡MOB)=25° =>m(∡AOB)=2·25=50° (OM-bisectoare)
=>m(∡BOC)=130° =>m(∡MOC)=25+130=155°