shoot, I hat proofs
definition of angle bisector:
didivide the angle in 2 parts
therefor the 2 angles that made up the prvious 1 angle are equal in measure
so
1. given
2. angle 1=angle 2
3. angle 3=angle 4
4. dunno
5. I think it is the SAA where if 1 side and 2 angles are congruent, then the triangles are similar
6. don't remember but something about in similar triangles, coresponding angles are congruent
