3已知:如图1.正方形ABCD,过点A作∠EAF=90°,两边分别交直线BC于点E,交线段CD于点F,G为AE中点,连接BG(1)求证:△ABE≌△ADF(2)如图2,过点G作BG的垂线交对角线AC于点H,求证:GH=GB;(3)如图3,连接HF,若CH=3AH,AD=210,求线段HF的长.ADADADFHFFGGGHEBCEBCEBC图1图2图3 ...