请你做出我上传题目的讲解视频---**Question:** 4、如图，四边形 ABCD 为正方形，DE // AC，且 CE = CA，直线 EC 交 DA 延长线于 F. **Statement to prove:** 求证：AE = AF. **Chart Description:** * **Type:** Geometric diagram. * **Main Elements:** * **Points:** A, B, C, D, E, F. * **Shapes:** Square ABCD. * **Lines/Segments:** * Segments forming the square ABCD. * Diagonal AC of the square. * Segment DE. * Segment CE. * Segment AE (drawn as a dashed line in many geometry problems, but depicted as a solid line here). * Segment AF (part of the extended line DA). * Line segment BF and CF are also shown. * **Relationships:** * ABCD is a square. * DE is parallel to AC (DE // AC). * Length of CE is equal to the length of CA (CE = CA). * Line EC intersects the extension of line DA at point F. * **Labels:** Points are labeled A, B, C, D, E, F. There is also a text label "考试资料" (Exam material) near point C. * **Configuration:** The points A, B, C, D form a square in a roughly vertical orientation with BC at the bottom. Point E is to the right and slightly below C. Point F is to the left of A, on the extension of DA upwards. Line DE is parallel to AC. Line EC passes through C and E, and extends to intersect the line passing through D and A (extended upwards) at F. Segments are drawn connecting A to C, B to D (diagonal of square), A to E, A to F, B to F, C to F. (Note: BF and CF are drawn in the diagram but not explicitly mentioned in the problem statement). Point B and C appear to be on a horizontal line. Point A and D appear to be on a vertical line above B and C respectively. F is on the line containing A and D, above A. E is to the right of D and C. **Other Relevant Text:** 考试资料 (Exam material)