如图,在△ABC中,AB=AC,AD⊥BC于点D,BE⊥AC于点E,交AD于点H,且AE=BE.求证:AH=2BD.

来源:学生作业帮助网 编辑:作业帮 时间:2024/06/13 13:07:27
如图,在△ABC中,AB=AC,AD⊥BC于点D,BE⊥AC于点E,交AD于点H,且AE=BE.求证:AH=2BD.
x]kPǿJ) Mi39)V%/M[uk]+WZ(cTDX± mG)MZ|NN`7;V oL^Ę&:66'pf&"LMO>b_b ZgoK-*F{n4tTcӕf&LZԚFƱÌ[W]UVdSȋШ7zyȶ8s:,T-'xb6ﺎU%_R]_VYʲo弣\)s(K(YƢ&,`UmVD_v5U=M+eidzJv[ Ny5&t:[TE4 {\#a`ߝ`!*t, EF1v»5 5!{,BpyOfa`y(_#O}2=j:1-& FI)bݨiKtw_^÷(Jcq]Bu{3p!2`31뎳ic%21N7aAk>%mM :dc 8Er\ AX\

如图,在△ABC中,AB=AC,AD⊥BC于点D,BE⊥AC于点E,交AD于点H,且AE=BE.求证:AH=2BD.
如图,在△ABC中,AB=AC,AD⊥BC于点D,BE⊥AC于点E,交AD于点H,且AE=BE.求证:AH=2BD.

如图,在△ABC中,AB=AC,AD⊥BC于点D,BE⊥AC于点E,交AD于点H,且AE=BE.求证:AH=2BD.
证明:延长BE使HE=EF,连接AF
BE⊥AC,HE=EF,易知△AHF是等腰三角形
∠HAE=∠EAF,AH=AF
AD⊥BC,BE⊥AC
∠HDB=∠AEH=90°
因∠HBD+∠BHD=∠HAE+∠AHE=90°,
∠BHD=∠HAE
所以∠HBD=∠AHE又∠HAE=∠EAF
∠HBD=∠EAF,BE=AE,∠BEC=∠AEF=90°
RT△BEC≌RT△AEF(ASA)
BC=AF
AH=AF
BC=AH,BC=2BD
AH=2BD

证明:
∵△ABC中,AB=AC,AD⊥BC于点D
∴BD=DC, ∠ABC=∠BCA,
∵AD⊥BC于点D,BE⊥AC于点E,∠BCA是公共角
∴△BCE∽△ACD
∴∠EBC=∠CAD
∵BE=AE,∠AEH==90°=∠BEC
∴△AHE≌△BCE
∴AH=BC=2BD