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有关圆的知识是初中几何中的重要内容之一.圆和直线的结合、圆和圆的结合等,使与圆有关的角之间的关系更加复杂.掌握这些角之间的内在联系,可使证明过程简捷.例1 已知:如图1,AB、AC是圆的两条弦,D、E分别为AB、AC的中点,DE分别交AB、AC于M、N两点.求证:AM=AN.分析:AM、AN在同
The knowledge about circles is one of the important contents of junior high school geometry. The combination of circles and lines, the combination of circles and circles, etc., make the relationship between the angles related to circles more complicated. Mastering the internal relations between these angles can be Make the proof process simple. Example 1 Known: Figure 1, AB, AC is a two-string circle, D, E, respectively, AB, AC midpoint, DE respectively AB, AC in M, N two points. Proof : AM = AN. Analysis: AM, AN in the same