1.如圖1,在△ABC中,∠A=90°,AB=AC=
+1,點D,E分別在邊AB,AC上,且AD=AE=1,連接DE.現(xiàn)將△ADE繞點A順時針方向旋轉(zhuǎn),旋轉(zhuǎn)角為α(0°<α<360°),如圖2,連接CE,BD,CD.
(1)當(dāng)0°<α<180°時,求證:CE=BD;
(2)如圖3,當(dāng)α=90°時,延長CE交BD于點F,求證:CF垂直平分BD;
(3)在旋轉(zhuǎn)過程中,求△BCD的面積的最大值,并寫出此時旋轉(zhuǎn)角α的度數(shù).