Since the three sides are equal it can be easy to use SSS criteria to prove triangles ABC and ADC are congruent.

It is not given that BAC and DAC are equal.

Therefore, it cannot be assumed that angle BAC and DAC are equal.

Since, it is also given that one angle is equal. therefore, it is easy to use SSS criteria.

Thus, the SAS congruence criteria cannot be use even though it looks like angle BAC and DAC are equal.

It is not given that BAC and DAC are equal.

Therefore, it cannot be assumed that angle BAC and DAC are equal.

Since, it is also given that one angle is equal. therefore, it is easy to use SSS criteria.

Thus, the SAS congruence criteria cannot be use even though it looks like angle BAC and DAC are equal.