Răspuns:
Explicație pas cu pas:
a) arc(ABC)=arc(AB)+arc(BC)=80°+130°=210°
b) arc(BCD)=arc(BC)+arc(CD)=130°+110°=240°
c) arc(AD)=360°-[arc(AB)+arc(BC)+arc(CD)]=360°-(80°+130°+110°)=360°-320°=40°
d) ∡BOD=arc(BD)=arc(AB)+arc(AD)=80°+40°=120°
