∵OE平分∠BOD∴∠BOE=∠DOE=1/2∠BOD∵∠AOD+∠BOD=180°，∠AOD:∠BOE=4:1即∠AOD=4∠BOE=4×1/2∠BOD=2∠BOD∴2∠BOD+∠BOD=180°∠BOD=60°∴∠AOD=120°∠BOE=1/2∠BOD=30°∵∠BOC=∠AOD=120°∴∠COE=∠BOC+∠BOE=120°+30°=150°∵OF平分∠COE∴∠EOF=1/2∠COE=1/2×150°=75°
