The correct answers are:
∆ABC and ∆DEF may or may not be congruent.
AAA is not a criterion for congruency of any two triangles.
Here's why:
Criteria for Congruency of Triangles:
SSS (Side-Side-Side): If all three corresponding sides of two triangles are equal in length, then the triangles are congruent.
SAS (Side-Angle-Side): If two corresponding sides and the included angle between them are equal in two triangles, then the triangles are congruent.
ASA (Angle-Side-Angle): If two corresponding angles and the included side between them are equal in two triangles, then the triangles are congruent.
AAS (Angle-Angle-Side): If two corresponding angles and a non-included side are equal in two triangles, then the triangles are congruent.
AAA (Angle-Angle-Angle):
While AAA does ensure that two triangles are similar (meaning they have the same shape but not necessarily the same size), it does not guarantee congruency.
To see this, imagine two triangles with the same angle measures but different side lengths. They would have the same shape, but they wouldn't be exactly the same size, so they wouldn't be congruent.
Therefore, if ∆ABC and ∆DEF satisfy the AAA correspondence, they are definitely similar, but they may or may not be congruent. It depends on whether their corresponding sides are also equal in length.