You may only use elementary geometry, such as the fact that the angles of a triangle add up to 180 degrees and the basic congruent triangle rules (side-angle-side, etc.).

你可以使用初等的几何知识例如三角形的三个内角各为180度和三角形全等的规则(边-角-边等)。

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Angle-angle-side congruence. when two triangles have corresponding angles and sides that are congruent as shown below the triangles are congruent .

译：当两个三角形象下面所示有两个角和一个边同时相等时，这两个三角形全等。

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