解题过程需配合图进行展示---**Textual Information:** * **Question Stem:** 如图, 已知AB=CD, 求∠C=? * Translation: As shown in the figure, given AB=CD, find ∠C=? **Chart/Diagram Description:** * **Type:** Geometric figure (Triangle with a segment inside). * **Main Elements:** * **Points:** Points labeled A, B, C, and D. * **Lines:** Line segments forming a triangle ABC. Point D is on the line segment BC. A line segment AD connects point A to point D. * **Angles:** * Angle at vertex B (∠ABC) is labeled as 40 degrees. * Angle ∠BAD is labeled as 30 degrees. * **Labels and Annotations:** Points A, B, C, D are labeled. Angle B is labeled 40 degrees. Angle BAD is labeled 30 degrees. * **Relative Position:** Point D is on the line segment BC, located between B and C.