(1)∠AOD与∠COB互补;理由是:
∵∠AOB=∠COD=90°
∴∠COB=∠AOB-∠AOC
=90°-∠AOC
∵∠AOD+∠COB
=∠AOC+∠COD+∠COB
=(∠AOB-∠COB)+90°+∠COB
=(90°-∠COB)+90°+∠COB
=180°
∴∠AOD与∠COB互补;
(2)这时(1)中得结论成立;理由是:
∵∠AOD+∠AOB+∠COB+∠COD=360°
且∠AOB=∠COD=90°
∴∠AOD+90°+∠COB+90°=360°
∴∠AOD+∠COB=180°
【很高兴为你解决以上问题,希望对你的学习有所帮助!】≤、≥ ∠