题目

The woman has an (优雅的) manner, but she is extremely difflcult to work with. 答案：【1】elegant（本题满分10分）已知：如图，△ABC中，AD⊥BC，AB=AE，点E在AC的垂直平分线上.（1）请问：AB、BD、DC有何数量关系？并说明理由.（2）如果∠B=60°，证明：CD=3BD.