纵观近几年全国各地的高考,对抛物线几何性质的考查几乎年年不漏,而且有相当多的省、市对抛物线的考查以难题出现.仔细分析这些考题后发现,焦点弦问题是常考常新的重要题型.本文就解决抛物线焦点弦问题的有力武器——特征梯形的性质,作详细地介绍.一、性质 Throughout the college entrance examination in recent years across the country, the parabolic geometric nature of almost no leaks, but there are a considerable number of provinces, municipalities to parabolic test difficult problems appear.After careful analysis of these test questions found that the focus of the string problem is often This paper is a detailed description of the nature of the trait that is the powerful weapon to solve the chord problem of parabola - characteristic trapezoid.