没看见图,就两种情况说一下:
(1)E、F在AB线同侧时,∠AOF与∠DOE、∠BOF与∠COE分别互补,即和是180°.
∠AOD=∠COB ∠AOD+∠AOF=∠COB +∠COE=90° 故:∠AOF=∠COE
而∠COE+∠DOE=180°所以:∠AOF+∠DOE=180°
同理可证∠BOF+∠COE=180°
(1)E、F在AB线两侧侧时,∠AOF=∠DOE、∠BOF=∠COE
∠AOF+∠DOA=90° ∠DOE+∠DOA=90°所以:∠AOF=∠DOE
∠BOF=∠BOC+90° ∠COE=∠BOC+90°所以:∠BOF=∠COE