25.已知△ABC,∠ACB=90°,AC=BC=4,D是射線CB上一點(diǎn),聯(lián)結(jié)AD,將AD繞點(diǎn)A逆時(shí)針旋轉(zhuǎn)90°,點(diǎn)D落在點(diǎn)E處,聯(lián)結(jié)BE交射線AC于點(diǎn)F.
(1)如圖1,當(dāng)點(diǎn)D與點(diǎn)C重合時(shí),求AF的長(zhǎng);
(2)如圖2,當(dāng)點(diǎn)D在線段BC上時(shí),聯(lián)結(jié)CE,在點(diǎn)D的運(yùn)動(dòng)過(guò)程中,請(qǐng)問(wèn)△AEC的面積是否會(huì)發(fā)生變化?如果不會(huì),求出它的面積;如果會(huì),請(qǐng)說(shuō)明理由;
(3)當(dāng)BD=1時(shí),求AF的長(zhǎng).