a: góc ABH+góc HAD=90 độ
góc AHD+góc HAD=90 độ
=>góc ABH=góc AHD
góc ABH=góc HAC
góc HAC=góc AHD
=>góc ABH=góc AHD
b: góc ACH+góc HAC=90 độ
góc AHF+góc HAC=90 độ
=>góc ACH=góc AHF
góc ACH=góc HAB
góc HAB=góc AHF
=>góc ACH=góc AHF
c: góc HAF=góc AHD
góc AHD=góc B
=>góc HAF=góc B
d: góc HAD=góc AHF
góc AHF=góc HCA
=>góc HAD=góc HCA