(1)∵∠AOD=∠BOC(对顶角相等)
∴∠AOD=80°
又∵OE平分∠BOC
∴∠BOE= ∠BOC= ×80°=40°
又∵∠AOF=∠BOE(对顶角相等)
∴∠AOF=40°
(2)OF平分∠AOD
∵∠AOD=80°,∠AOF=40°
∴∠FOD=80°-40°=40°
即∠AOF=∠FOD
∴OF平分∠AOD
(1)∵∠AOD=∠BOC(对顶角相等)
∴∠AOD=80°
又∵OE平分∠BOC
∴∠BOE= ∠BOC= ×80°=40°
又∵∠AOF=∠BOE(对顶角相等)
∴∠AOF=40°
(2)OF平分∠AOD
∵∠AOD=80°,∠AOF=40°
∴∠FOD=80°-40°=40°
即∠AOF=∠FOD
∴OF平分∠AOD