CB平行于AB...错了吧CD平行于AB证明：延长CE交DA延长线与F设∠EDC =∠1 ∠ECD =∠2∠1+∠2=90则∠CED=180-∠1-∠2=90∠DEF=90=∠DEA+∠AEF=∠EDA+∠DFECD平行AB∠1=∠DEA=∠EDA所以∠AEF=∠2∠AFE=∠1所以∠EAF=∠EA...