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解决直线形问题,要方法活,方法新,有独到之处. 全等三角形是有关直线形问题中的一个重点,而全等三角形是进一步证明相等线段或相等角的一种重要途径.当通过全等三角形来证明两线段(或两个角)相等时,若它们所在的两个三角形不全等,就必须添加辅助线.常见辅助线有:①连结两个已知点;②经过已知点,作已知直线的平行线;③延长某已知线段到某个点;④作一个角等于已知角.
Solve the linear problem, to live method, new method, there is a unique place. Congruent triangle is a key point in the linear problem, and congruent triangle is an important way to further prove the equal line segment or equal angle. Congruent triangles to prove that two line segments (or two corners) are equal, if they are in two triangles are not equal, you must add auxiliary lines. Common auxiliary lines are: 1 to connect two known points; 2 through known points , make a parallel line of a known straight line; 3 extend a known line segment to a certain point; 4 make an angle equal to a known angle.