证明:
∵AB=AD,AC=AE
且∠DAC=∠DAB+∠BAC=90°+∠BAC=∠EAC+∠BAC=∠BAE
即∠DAC=∠BAE
∴△DAC≌△BAE(SAS)
∴∠B=∠D
∴∠BHD
=180°-∠B-∠BNH
=180°-∠D-∠AND
=∠BAD
=90°
即BE垂直于CD
证明:
∵AB=AD,AC=AE
且∠DAC=∠DAB+∠BAC=90°+∠BAC=∠EAC+∠BAC=∠BAE
即∠DAC=∠BAE
∴△DAC≌△BAE(SAS)
∴∠B=∠D
∴∠BHD
=180°-∠B-∠BNH
=180°-∠D-∠AND
=∠BAD
=90°
即BE垂直于CD