2.四邊形ABCD中,AD∥BC,∠BAC=∠D,點(diǎn)E在BC邊上運(yùn)動(dòng)(不與C重合),點(diǎn)F在CD上運(yùn)動(dòng),且∠AEF=∠ACD.
(1)若AB=BC=CA,判斷AE與EF的數(shù)量關(guān)系;
(2)若AB=BC,你在(1)中得到的結(jié)論是否會(huì)發(fā)生變化?寫出猜想并給出證明;
(3)若AB=AC=5,
,∠BAC為銳角,設(shè)EF=t,當(dāng)E,F(xiàn)運(yùn)動(dòng)時(shí),求t的取值范圍.