1、∵∠AOB=∠AOC+∠BOC=180°
OE平分∠AOC，OD平分∠BOC
∴∠COE=1/2∠AOC，∠COD=1/2∠BOC
∴∠DOE=∠COE+∠COD=1/2(∠AOC+∠COD)=90°
2、互余：∠COE和∠COD，∠COE和 ∠BOD
∠AOE和∠COD，∠AOE和∠BOD
互补的角:∠AOE和∠BOE
∠AOC和∠BOC
∠AOD和∠BOD
