在△ABC中，DE，DF分别为BC，AB边的垂直平分线，连接AD，CD．（1）若∠B = 40°，求∠ACD的度数；（2）判断∠B与∠ACD之间的数量关系，并说明理由．---**Extraction Content:** **Geometric Diagram Description:** * **Type:** Geometric figure (Triangle with internal points and lines). * **Main Elements:** * **Points:** Points labeled A, B, C, D, E, F. * **Lines/Segments:** * Triangle ABC with sides AB, BC, and CA. * Point D is located inside triangle ABC. * Point E is located on side BC. * Point F is located on side AB. * Line segments connect: A to D, C to D, B to D, D to E, and D to F. * Segment DF is perpendicular to segment AB, indicated by a right-angle symbol at point F. * **Relative Position:** D is inside the triangle. E is on side BC. F is on side AB. DF forms a perpendicular line from D to the side AB. DE connects D to a point on side BC. AD, BD, CD connect D to the vertices A, B, and C, respectively. **Other Relevant Text:** * No question stem text is visible in the image. * No options (A, B, C, D) are visible in the image. * No mathematical formulas or equations are visible. * No table content is visible. * No chart titles, units, or annotations other than point labels and the right-angle symbol at F are visible.