3.如圖,在邊長(zhǎng)為4的正方形ABCD中,E為CD邊上一點(diǎn).
(1)如圖(1),將射線AE繞點(diǎn)A順時(shí)針旋轉(zhuǎn)90°后交CB的延長(zhǎng)線于點(diǎn)F,求四邊形AFCE的面積;
(2)如圖(2),若E是CD的中點(diǎn),G是BC邊上一點(diǎn),將線段AG繞點(diǎn)G順時(shí)針旋轉(zhuǎn)90°后得到線段HG,點(diǎn)H恰好落在射線AE上,求證:CG=2BG;
(3)如圖(3),若DE=3CE,點(diǎn)M在正方形ABCD的對(duì)角線AC上,且∠BME=135°,請(qǐng)直接寫出AM的長(zhǎng)度.