23.已知:在△ABC中,BA=BC,點(diǎn)E是AC的中點(diǎn),F(xiàn)是直線BC上一點(diǎn),連接EF,將△EFC沿著EF折疊,點(diǎn)C的對應(yīng)點(diǎn)為D,連接AD.
(1)如圖1,若點(diǎn)D在線段AB上,求證:EF∥AD;
(2)如圖2,DF與AB交于點(diǎn)M,連接AF,若∠DAF=∠EAF,求證:點(diǎn)M是AB的中點(diǎn);
(3)如圖3,點(diǎn)F在CB延長線上,DF與AB交于點(diǎn)M,EF交AB于點(diǎn)N,若DE=EN=3,BC=5,求MF?MA.