Answer:
SAS Congruence Postulate
Step-by-step explanation:
In ΔABC and ΔDCE
AC=CE [given]→Side
∠ACB=∠DCE [vertically opposite angles]→Angle
BC=DC [given]→Side
∴ ΔABC ≅ ΔDCE [SAS congruence postulate]
SAS congruence postulate tells that if two sides and the included angle of one triangle are congruent to two sides and the included angle of other triangle, then the two triangles are congruent.
This is SAS. Notice you have 2 sides that are equal to each other and the vertical angle between them. Since the angle is between the 2 sides then the postulate that works is SAS.
