To prove triangles \( \triangle ABC \cong \triangle CDA \) by the ASA (Angle-Side-Angle) Congruence Theorem, you already have the following information:
- \( \angle BCA \cong \angle DAC \) (given)
- \( \angle BAC \cong \angle DCA \) (given)
To complete the proof using the ASA criterion, you need to establish the congruence of one pair of sides that is included between the angles. In a parallelogram, opposite sides are congruent, so the additional information you need would be:
DA\(\cong\)BC by the properties of a parallelogram.
Justifying this, you can state:
- Opposite sides of a parallelogram are congruent. Therefore, \( DA \cong BC \).
Now you have:
- Two pairs of angles \( \angle BCA \cong \angle DAC \) and \( \angle BAC \cong \angle DCA \), and
- One pair of included sides \( DA \cong BC \).
Thus, you can conclude that \( \triangle ABC \cong \triangle CDA \) by the ASA Congruence Theorem.