The overlapping angles that are congruent by AAS are:
∠ADC ≅ ∠EBC
How to use Congruency Postulates?
There are different congruency postulates such as:
AAS
ASA
SAS
SSS
HL
In this case, we are given:
∠ADE ≅ ∠ABE = 90°
Similarly, we see that:
∠EBC ≅ ∠ADC = 90° by definition of perpendicular lines
We are also given that:
EC ≅ DC
We can also deduce that ∠ACD ≅ ∠ECB by reflexive property of congruence.
Thus, we can see that we are given two congruent angles and the non included side and so the triangles ∠EBC and ∠ADC are congruent by AAS Congruency.