(1)∵OM平分∠AOB,ON平分∠COD
∴∠BOM=1/2∠AOB,∠CON=1/2∠COD,
∴∠MNO
=∠MOB+∠BOC+∠CON
=1/2(∠AOB+∠COD)+∠BOC
=1/2(∠AOD-∠BOC)+∠BOC,
=1/2(∠AOD+∠BOC)
=1/2(α+β)
(2)∵∠BOM=α-∠BOC,∠CON=β-∠BOC,
∴∠AOB=2(α-∠BOC),∠COD=2(β-∠BOC),
又∵∠AOD-∠AOB-∠COD=∠BOC,
即γ-2(α-∠BOC)-2(β-∠BOC)=∠BOC
∴∠BOC=(2α+2β-γ)/3
∠MON=(α+β)/2
∠BOC=1/3(2α+2β-γ)