帮我讲讲这道题---**Question Number:** 9 **Question Stem:** 如图，把一张长方形纸条 ABCD 沿 EF 折叠，若 ∠1 = 61°，则 ∠AEG 的大小为 ( ) *(Translation: As shown in the figure, a rectangular paper strip ABCD is folded along EF. If ∠1 = 61°, then the size of ∠AEG is ( ))* **Options:** A. 55° B. 58° C. 61° D. 64° **Diagram Description:** * **Type:** Geometric figure illustrating a paper folding problem. * **Elements:** * Original shape: Rectangle ABCD. Vertices are labeled A, B, C, D in a counter-clockwise direction. AB is on the left, BC is at the bottom, CD is on the right, AD is at the top. * Folding line: Line segment EF. E is on AD, F is on BC. * Folded shape: The part ECDF is folded along EF to form EFC'D'. * New points: D' and C' are the folded positions of D and C, respectively. G is the intersection point of AB and ED'. * Lines: Original edges AB, BC, CD (partially dashed), AD (partially solid). Folding line EF. Folded edges ED' and D'C'. Line segment EG is shown. * Angles: ∠1 is labeled as the angle between line segment GD' and line segment EF, near point F. The value of ∠1 is given as 61°. The angle to be found is ∠AEG. * Relative positions: AB is parallel to CD, AD is parallel to BC. E is on AD, F is on BC. G is on AB. The fold is along EF, so EF is the fold line. E, F, C, D fold to E, F, C', D'. Line segment ED' intersects AB at G. * Implicit property due to folding: ∠DEF is folded onto ∠D'EF. Thus, ∠DEF = ∠D'EF. * Implicit property of rectangle: AD is parallel to BC. Therefore, AD is parallel to the line passing through E, G, F, and C. **Other Relevant Text:** * "如图" means "As shown in the figure".