生成这个题目的讲解---**Question Stem:** 如图，点D, E分别在△ABC的边AB, AC上，且DE//BC，点F在线段BC的延长线上。若∠ADE=28°, ∠ACF=118°，则∠A=90°。 **Chart/Diagram Description:** * **Type:** Geometric figure, specifically a triangle (△ABC) with an internal line segment parallel to one side, and an extension of one of its sides. * **Main Elements:** * **Triangle ABC:** A triangle with vertices labeled A (top), B (bottom left), and C (bottom right). * **Points D and E:** Point D is located on side AB. Point E is located on side AC. * **Line Segment DE:** Connects point D and point E, drawn horizontally within the triangle. * **Line Segment BC:** The base of the triangle. * **Point F:** Located on the line that extends from B through C, specifically to the right of C. * **Relationship:** Line segment DE is parallel to line segment BC (DE//BC). **Other Relevant Text (Solution):** **解：** ∵ DE // BC, ∴ ∠B = ∠ADE = 28°, 又∵ ∠ACF = ∠A + ∠B, ∴ ∠A = ∠ACF - ∠B = 118° - 28° = 90°. 故答案为: 90°.