连接DE∵∠ADB=∠AEB=90度∴A、B、D、E四点共圆∴∠ADE=∠ABE∵∠EAO=∠DAC∠AEO=∠ADC∴ΔAEO∽ΔADC∴AE/AO=AD/AC∴ΔEAD∽ΔOAC∴∠ACF=∠ADE=∠ABE又∵∠ABE+∠BAC=90度∴∠ACF+∠BAC=90度∴CF⊥AB∴∠ABC+∠FCD=90请点击“采纳为答案”
