Question

如图,在三角形ABC中,∠BAC=120°,AB=AC,点D在BC上,且BD=BA,点E在BC的延长线上,且CE=CA

Answer 1

（2）由BD=BA,可得∠BAD=∠BDA=∠DAE+∠DEA,即∠BAD+∠DAE=∠BAC+∠CAE=α+∠CAE,又由于CE=CA,得∠DEA=∠CAE,所以由∠BAD=∠DAE+∠CAE和∠BAD+∠DAE=α+∠CAE,∠DAE=α/2.（1）∠DAE=60