Question

triangle def is congruent to △def by the sss theorem. which single rigid transformation is required to map △def onto △def?
○ dilation
○ reflection
○ rotation
○ translation

Explanation:

Step1: Recall properties of rigid transformations

Dilation changes size (not rigid). Reflection flips over a line. Rotation turns around a point. Translation slides without rotation/flip.

Step2: Analyze congruent triangles

Since \(\triangle DEF\cong\triangle D'EF'\) (by SSS) and the orientation seems mirrored (a common sign of reflection). A reflection over a line (e.g., line \(EF\) or a line perpendicular to \(DD'\) at its mid - point) can map \(\triangle DEF\) to \(\triangle D'EF'\) as rigid transformation.

Answer:

reflection