∵AE=C'G,AA'=CC',
∴≌A'E=CG;
∴≌A'F=CH;
又在Rt△AEF和Rt△C'GH中,
AE=C'G,AF=C'H,
∴RtAEF≌Rt△C'GH, EF=GH.
∴△A'EF≌△CGH,
∴∠EA'F=∠GCH.