24.已知正方形ABCD的邊長為4..
(1)如圖1,點(diǎn)P在直線AD上運(yùn)動(dòng),連接 PC,將線段PC繞點(diǎn)C按順時(shí)針旋轉(zhuǎn)90°得到CE,連接BE.
①若點(diǎn)P與A重合,則BE=
.
②若BE=9,求AP的長.
(2)如圖2,點(diǎn)P在邊AD上(P不與A,D重合)運(yùn)動(dòng),且PA>PD,連接PB、PC.將線段PB繞點(diǎn)P逆時(shí)針旋轉(zhuǎn)90°得到PM,將線段PC繞點(diǎn)P順時(shí)針旋轉(zhuǎn)90°得到PN,設(shè)PD=x,MN=y,求y關(guān)于x的函數(shù)表達(dá)式.
??