Question

如图，O是直线AB上一点，OC为任一条射线，OD平分∠AOC；OE平分∠BOC．

1.写出图中∠BOD与∠AOE的补角；

2.如果∠COD=25°，那么∠COE=_______；如果∠COD=60°，那么∠COE=________；

3.试猜想∠COD与∠COE具有怎样的数量关系，并说明理由．

Answer

1.∠BOD的补角为∠AOD,∠DOC ；

∠AOE的补角为∠BOE,∠EOC．        ·························4分

2.65°；30°．               ·······························6分

3.∠COD+∠COE=90°．   ······································7分

因为OD平分∠AOC,OE平分∠BOC．

所以 ∠COD=∠AOC ， ∠COE=∠BOC．

所以∠COD+∠COE=∠AOB=180°=90°． ··················10分

 【解析】略