To determine the single rigid transformation that maps triangle \( \triangle ABC \) to triangle \( \triangle EDC \), we can analyze the congruence and positioning of the triangles.
Given that:
- \( \triangle ABC \) and \( \triangle EDC \) share vertex \( C \).
- Sides \( BC \) and \( CD \) are congruent.
- Angles \( A \) and \( E \) are congruent.
- Angle \( C \) is congruent in both triangles.
These properties suggest that \( \triangle ABC \) can be placed onto \( \triangle EDC \) through a specific transformation.
Since \( \angle C \) is a vertex common to both triangles and the two pairs of corresponding sides are congruent, a reflection across line segment \( CD \) would align the corresponding angles and sides.
Therefore, the correct transformation that maps \( \triangle ABC \) to \( \triangle EDC \) is:
reflection