Answer: We need AB = CD to be true so we could use SAS
Reason
We already have AC = AC as one pair of congruent sides, due to the reflexive property. This forms one "S" of "SAS".
The angle markers help us form the "A" of "SAS"
The last "S" refers to AB and CD. If they were congruent segments, then we can use SAS to prove that triangle ABC = triangle CDA.
Notice that the angles mentioned are between the sides mentioned.