⑴.CE=CF.AG=BG,DG=CG,AE=AF.
⑵.CE=CF:∵AB‖DC,AD=DC=CB.∴ABCD为等腰梯形,∠DAB=∠CBA.∠GBC=∠GAB
∴∠GDC=∠GBA.⊿CED≌⊿CFB(A,A,S),∴CE=CF.