题目

We're having a meeting in halfan hour. The decision (make) at the meeting will influence the futureof our company. 答案：【1】to be made如图，E、F分别为△ABC的边BC、CA的中点，延长EF到D，使得DF=EF，连接DA、DB、AE．（1）求证：四边形ACED是平行四边形；（2）若AB=AC，试说明四边形AEBD是矩形．