To prove that triangle \( \triangle ABC \) is congruent to triangle \( \triangle A''B''C'' \) using the Angle-Side-Angle (ASA) criterion and the definition of congruence in terms of rigid motions, we can break down the process:
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Identify the Corresponding Parts: We need to align the angles and the side of one triangle with those of the other triangle. The ASA criterion states that if two angles and the included side of one triangle are equal to two angles and the included side of another triangle, then the triangles are congruent.
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Applying Rigid Motions: Rigid motions (rotations, reflections, and translations) preserve distances and angles. We can use these to show that one triangle can be transformed into the other.
The correct approach from the options you've provided should include:
- A rotation about a vertex: This helps position one angle to match the corresponding angle of the other triangle.
- A reflection across a side: This aligns the triangles.
Among the responses you listed, the options are somewhat similar in structure, but it is important to choose the one that properly applies the ASA principle.
Response that Fits ASA: "Rotate \( \triangle ABC \) \( -90 \) degrees (clockwise) about vertex \( C \), and then reflect \( \triangle A'B'C' \) across \( CA' \)."
This response takes one angle of \( \triangle ABC \) and manipulates it so that it corresponds with the angle of \( \triangle A'B'C' \), which helps satisfy the ASA conditions.
Therefore, effectively applying both rigid motions above will result in \( \triangle ABC \) being transformed into \( \triangle A''B''C'' \), proving their congruence.