题目
如图,射线OA、OC在射线OB的异侧且∠BOC = 2∠AOB (∠AOB<60°),射线OD平分∠AOC,请探求∠BOD与∠AOB的数量关系.
答案:解: ∠AOB=2∠BOD;理由如下:∵OD平分 ∠AOC,∴∠COD=∠AOD,∵∠BOC=∠COD+∠BOD,∠AOB=∠AOD-∠BOD,∠BOC = 2∠AOB,∴∠COD+∠BOD=2(∠AOD-∠BOD),即∠AOD+∠BOD=2∠AOD-2∠BOD,∠AOD=3∠BOD,∴∠AOB=∠AOD-∠BOD=3∠BOD-∠BOD=2∠BOD.