学习了平行线分线段成比例定理后,两线段相等又多了一类证法——用比例证线段相等.现归纳其常见类型.一.a/c=b/c型欲证线段a,b相等,在图形中找到线段c,设法证明a/c=b/c,从而得到a=b.例1一直线和梯形ABCD的底AD平行,和AB、BD、AC、CD分别交于E、 After studying the proportional theorem of the parallel line subdivision line segment, the two line segments are equal and there is one more type of syndrome pattern - with the same proportion of the line segments, the common types are summarized as follows: a. A / c = b / b is equal to find the line segment c in the graph, trying to prove that a / c = b / c, resulting in a = b. Example 1 a straight line and the trapezoidal ABCD bottom AD parallel, and AB, BD, AC, ,