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梯形是一种特殊的四边形,它是平行四边形和三角形的综合.通过适当地添加辅助线,可以把梯形问题转化为三角形、平行四边形的组合图形,再运用三角形、平行四边形的知识,可以顺利解决梯形的有关问题.本文试就梯形问题中辅助线添加的常用类型进行讨论.一、平移一腰过梯形上底的一个顶点作一腰的平行线,构造出一个平行四边形和一个三角形,即平移一腰来解决问题.例1如图1,梯形ABCD中,AB∥CD,
Trapezoid is a special kind of quadrilateral, which is a combination of parallelogram and triangle. By adding auxiliary lines properly, the problem of trapezoid can be transformed into the combination of triangle and parallelogram, then the knowledge of triangle and parallelogram can be successfully solved Trapezoid-related problems.This paper tries to discuss the common types of auxiliary lines added in the trapezoidal problem.First, a parallel line parallel to the waist and parallel to a vertex of the trapezoidal upper bottom is translated, a parallelogram and a triangle are constructed, that is, translation A waist to solve the problem. Example 1 Figure 1, trapezoidal ABCD, AB ∥ CD,