如图是两个全等三角形，图中的字母表示三角形的边长，则∠1的度数是（　　）

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                                                                                          次北固山下
                                                                                                王湾
                                                                                 客路青山外，行舟绿水前。
                                                                                 潮平两岸阔，风正一帆悬。
                                                                                 海日生残夜，江春入旧年。
                                                                                 乡书何处达？归雁洛阳边。