解题过程，并演示动画。创立知识点，及初中数学知识点关联。---**Question Number:** 2
**Question Stem:**
如图, AB//CD, BE 平分 ∠ABC, CE 平分 ∠BCD, 若 E 在 AD 上.
求证:
(1) BE⊥CE;
(2) BC=AB+CD.
**Translation of Question Stem:**
As shown in the figure, AB is parallel to CD, BE bisects ∠ABC, CE bisects ∠BCD, if E is on AD.
Prove:
(1) BE⊥CE;
(2) BC = AB + CD.
**Diagram Description:**
* **Type:** Geometric figure (quadrilateral ABCD with a point E on AD and segments BE and CE).
* **Main Elements:**
* **Points:** A, B, C, D, E.
* **Lines:** Line segments AB, BC, CD, DA, BE, CE.
* **Relative Position:** Points are labeled as A, B, C, D, and E. Point E is located on the line segment AD. Segments are drawn connecting A to B, B to C, C to D, D to A, B to E, and C to E. This forms a quadrilateral ABCD and two internal segments BE and CE from vertices B and C to a point E on the opposite side AD.
* **Relationships (from text):**
* Line AB is parallel to line CD (AB//CD).
* Line segment BE bisects angle ABC.
* Line segment CE bisects angle BCD.
* Point E lies on line segment AD.