给我讲解一下---**Question Number:** 8. **Title:** 分类讨论思想 (Classification Discussion Thought) **Context:** (2024 · 郑州高新区期末) **Question Stem:** 图, 在△ABC中, ∠A = 50°, ∠B = 28°, D是线段AB上一个动点, 连接CD, 把△ACD沿CD折叠, 点A落在同一平面内的点A'处. 当A'D平行于△ABC的一边时, ∠ACD的大小为 **Handwritten Notes/Possible Answers:** Notes in red and black ink near the question and at the end include: 30°, 76°, 65°, "或", "30°或76°或65". **Image Description:** * **Type:** Geometric diagram illustrating a triangle and a reflection. * **Main Elements:** * A triangle with vertices labeled A, B, C. * A point D is located on the side AB. * A line segment CD connects vertex C to point D. * A point A' is shown, representing the reflection of point A across the line CD. * Line segments A'D and A'C are drawn. A'C is a solid line, and A'D is a solid line. * A dashed line connects A to A', indicating the fold line (reflection axis is CD). * An arc with a dot is marked near angle A'DC. * The vertices A, D, B appear collinear, forming the side AB of the triangle. * The point C is not on the line containing A, D, B.