
如图1,在△ABC中,∠BAC=90,AB=AC,AO⊥BC如图1,在⊿ABC中,∠BAC=90°,AB=AC,AO⊥BC
如图1,在△ABC中,∠BAC=90,AB=AC,AO⊥BC如图1,在⊿ABC中,∠BAC=90°,AB=AC,AO⊥BC于点O,F是线段AO上的点(与A、O不重合),∠EAF=90°,AE=AF,连接FE,FC,BF. (1)求证:BE=BF;(2)如图2,若将⊿AEF绕点A旋转,使边AF
如图1,在△ABC中,∠BAC=90,AB=AC,AO⊥BC
如图1,在⊿ABC中,∠BAC=90°,AB=AC,AO⊥BC于点O,F是线段AO上的点(与A、O不重合),∠EAF=90°,AE=AF,连接FE,FC,BF.
(1)求证:BE=BF;
(2)如图2,若将⊿AEF绕点A旋转,使边AF在∠BAC的内部,延长CF交AB于点G,交BE于点K.
①求证:⊿AGC∽⊿KGB;
②当⊿BEF为等腰直角三角形时,请直接写出AB:BF的值.
证明:1,证BE=BF,很简单,
∵∠BAC=90°,AB=AC,AO⊥BC,
∴∠OAB=45°
∵∠EAF=90°
∴∠EAB=45°
又AE=AF
∴⊿AEB≌⊿AFB
∴BE=BF
2,(1)∵∠EAB+∠FAB=90°
∠FAC+∠FAB=90°
∴∠EAB= ∠FAC
AE=AF,AB=AC
∴⊿AEB≡⊿AFC
∴∠EBA= ∠FCA
又∠KGB= ∠AGC
∴⊿AGC∽⊿KGB
(2)∵⊿BEF为等腰直角三角形,∠EAF=90°,AE=AF
∴AE=AF=BE=BF
∴AB:BF=√2