Because AE=CF
So AE+EF=CF+EF
So AF=CE
It should be BF vertical CE, so ∠BFA equals 90.
It should be DE vertical AC, so ∠DEC=90.
In ABF and CDE.
AB=CD
AF=CE
So RT△ABF=RT△CDE
So ∠BAE=∠DCF.
In △ABF and triangular CDF
∠BAE=∠DCF
AB=CD
∠BGA=∠CGD
So △ABF= triangle CDF
So af=cf
Because AE=CF
So EG=FG