讲解一下这个题目---**Question Text:** 如图所示，已知BD=4, CD=2, ∠ADB=60°, ∠C=45°, 求∠B **Translation:** As shown in the figure, it is known that BD=4, CD=2, ∠ADB=60°, ∠C=45°, find ∠B **Mathematical Information from Text:** * Given: BD = 4 * Given: CD = 2 * Given: ∠ADB = 60° * Given: ∠C = 45° * Find: ∠B **Geometric Diagram Description:** * **Type:** Geometric figure, specifically a triangle ABC with a point D on side BC. * **Main Elements:** * Points: Labeled vertices A, B, C and point D on BC. * Lines: Segments AB, AC, BC, and AD. BC is composed of segments BD and DC. * Angles: * Angle at D inside triangle ABD is ∠ADB, labeled as 60°. * Angle at C in triangle ADC (and ABC) is ∠C, labeled as 45°. * Lengths: * Length of segment BD is labeled as 4. * Length of segment CD is labeled as 2. * **Relative Position:** Point D lies on the line segment BC, between B and C. Point A is positioned such that it forms triangles ABD and ADC. * **Labels and Annotations:** Points A, B, C, D are labeled. The values 60° are marked near angle ADB, and 45° near angle C. The lengths 4 and 2 are indicated below segments BD and CD respectively.