Question 61 • Geometry: Concepts and Connections
Since AB is parallel to DE and CB is a transversal, ∠CBA and ∠CED are corresponding angles, so they are congruent. The triangles also share the angle at C, so that angle is congruent to itself by the reflexive property. Two pairs of congruent angles establish triangle similarity by the AA similarity theorem, so the answer is AA similarity theorem.
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