如图，在正方体ABCD-A1B1C1D1中，棱长AA1=2，E为CC1的中点。&nBsp;
(1) &nBsp;求证：B1D1 ⊥AE；&nBsp;
(2) &nBsp;求二面角C-AE-B的平面角的正切值；&nBsp;
(3) &nBsp;求点D1到平面EAB的距离．&nBsp;