阅读下面的诗歌 ，回答相关问题
                                                                                                     渡荆门送别
                                                                                                           李白
                                                                                         渡远荆门外，来从楚国游。
                                                                                         山随平野尽，江入大荒流。
                                                                                         月下飞天镜，云生结海楼。
                                                                                         仍怜故乡水，万里送行舟。

（Ⅰ）证明：平面 $BDE\perp$ 平面 $PCD$ ；

（Ⅱ）求二面角 $P-BD-E$ 的余弦值.

驾____      概____    隔____     拔____    娇____

架____      溉____     融____     拨____    矫____

不管是黄昏

还是初露曙色

茉莉花

总是白的