给这道题目创建讲解视频。---问题背景: ∠AOB = 90°, 点M、N分别在OA、OB上运动 (不与点O重合)。 (1)问题思考: 如图1, MP、NP分别是∠AMN和∠MNB的平分线, 则∠MPN = ____°。 (2)问题解决: 如图2, 若MC是∠AMN的平分线, MC的反向延长线与∠MNO的平分线交于点P。 ① 若∠MNO = 60°, 则∠P = ____°。 ② 随着点M、N的运动, ∠P的大小会变吗? 如果不会, 求∠P的度数; 如果会, 请说明理由。 (3)问题拓展: 在图2的基础上, 如果∠MON = α, 其余条件不变, 随着点M、N的运动 (如图3), 求∠P的度数 (用含α的代数式表示)。 --- Diagram Description: 图1: Type: Geometric figure. Main Elements: - Coordinate axes: Two perpendicular lines OA and OB meeting at O, forming ∠AOB. A right angle symbol is shown at O. OA is oriented vertically upwards, OB horizontally to the right. - Points: O (origin), A (on OA), B (on OB), M (on OA, between O and A), N (on OB, between O and B), P (a point). - Lines: Line segments MN, MP, NP. Lines OA and OB are axes/rays. - Labels: O, A, B, M, N, P. - Annotations: "图1" below the figure. 图2: Type: Geometric figure. Main Elements: - Coordinate axes: Two perpendicular lines OA and OB meeting at O, forming ∠AOB = 90°. A right angle symbol is shown at O. OA is oriented vertically upwards, OB horizontally to the right. - Points: O, A, B, M (on OA), N (on OB), C (a point such that MC is a ray), P (the intersection of the line extending MC backwards and the bisector of ∠MNO). - Lines: Line segment MN. Ray MC, with its backward extension passing through P. Ray NP is the bisector of ∠MNO. Lines OA and OB are axes/rays. - Labels: O, A, B, M, N, P, C. - Annotations: "图2" below the figure. A number "1" is placed near O. 图3: Type: Geometric figure. Main Elements: - Coordinate axes: Two lines OA and OB meeting at O, forming ∠AOB. The text indicates ∠MON = α in this context. OA is oriented upwards, OB to the right. - Points: O, A (on OA), B (on OB), M (on OA), N (on OB), C (a point such that MC is a ray), P (the intersection of the line extending MC backwards and the bisector of ∠MNO). - Lines: Line segment MN. Ray MC, with its backward extension passing through P. Ray NP is the bisector of ∠MNO. Lines OA and OB are axes/rays. - Labels: O, A, B, M, N, P, C. - Annotations: "图3" below the figure.