Ta có \(\widehat{CAD}=\widehat{BCA}+90^0\)

\(\widehat{KAB}=\widehat{HBA}+\widehat{H}=\widehat{BCA}+90^0\)

=> \(\widehat{CAD}=\widehat{KAB}\)

Xét \(\Delta CAD\)và \(\Delta KAB\)có :

CA = KA(gt)

AD = AB(gt)

\(\widehat{CAD}=\widehat{KAB}\)(cmt)

=> \(\Delta CAD=\Delta KAB\left(c.g.c\right)\)

=> \(\widehat{D_1}=\widehat{B_1}\)

Ta lại có : \(\widehat{B_1}+\widehat{B_2}=90^0\)nên \(\widehat{D_1}+\widehat{B_2}=90^0\)

=> \(CD\perp BK\)

Ta lại có : \(AH\perp BC\)

Do đó \(\Delta KBC\)có KH,BE,CD là ba đường cao nên chung đồng quy

Vậy AH,BE,CD đồng quy