1、∠AC=∠AE
2、∠AD=∠AB
3、∠DAC=∠BAC+∠DAB
∠BAE=∠BAC+∠CAE
∠DAC=∠BAE
△DAC全等于△BAE
∠AEB=∠ACD
4、∠FEC=∠AEC-∠AEB
∠ECF=∠ECA-∠ACD
∠FEC+∠FCE=∠AEC+∠ECA=90°
CD⊥BF
1、∠AC=∠AE
2、∠AD=∠AB
3、∠DAC=∠BAC+∠DAB
∠BAE=∠BAC+∠CAE
∠DAC=∠BAE
△DAC全等于△BAE
∠AEB=∠ACD
4、∠FEC=∠AEC-∠AEB
∠ECF=∠ECA-∠ACD
∠FEC+∠FCE=∠AEC+∠ECA=90°
CD⊥BF