Question

写出什么因为所以,还有每一步的理由

Answer 1

∵∠AOE+∠AOF=180°,∠AOE=40°

∴∠AOF=180°-∠AOE=180°-40°=140°

∵OC平分角AOF

∴∠COF=∠AOF /2=140°/2=70°

又∠COF=∠DOE(对顶角)

∴∠DOE=70°

∵∠AOE+∠BOE=∠AOB=90°

∴∠BOE=90°-∠AOE=90°-40°=50°

∴∠BOD=∠DOE-∠BOE=70°-50°=20°