1) NEI
2) AAS
3) NEI
in order to prove triangles congruent you need to know three parts are congruent, but you can only use these in certain orders.
SAS-
side angle side
the congruent angles are surrounded by two congruent sides so, the 3 other parts must be equal; a straight line connecting the two end points must be equal and the angles would also be congruent.
ASA-
angle side angle
the congruent sides have congruent angles on both sides so the extending lines will have the same slope and meet to form the remaining parts.
SSS-
side side side
if the sides are the same the angles will also be the same
AAS-
angle angle side
two congruent angles followed by a congruent side
