∵∠中枣AOB=½∠BOC，，∠COD=∠AOD=3∠AOB
∠AOB+∠BOC+∠COD+∠AOD=360°
所以2∠AOB=∠BOC，把其他三个角全用卖埋拆∠AOB代替
有∠AOB+∠BOC+∠COD+∠AOD=360°
∠AOB+2∠AOB+3∠AOB+3∠液谨AOB=360°
9∠AOB=360°
∠AOB=40°
∴∠COD=∠AOD=3∠AOB=120°
解：核弯或设∠AOB=x，则∠COB=2x，∠DOC=∠DOA=3x
x+2x+3x+3x=360
x=40°
∴闹敬∠AOB=40°，∠改伍DOC=120°