解析几何综合题是高考命题的热点内容之一.它们常常以解析几何知识为载体,综合函数、数列、向量、不等式、三角等知识,所涉及的知识点较多,对解题能力考查的层次要求较高,考生在解答时,往往表现为无从下手,或者半途而废.而事实上,这类问题总是与“判别式”有着不解之缘,因此研究判别式在圆锥曲线问题中的巧妙应用,能更好地引导学生掌握好圆锥曲线问题。一、利用判别式解决直线和圆锥曲线的位置关系问题 Analytic geometry synthesis questions are one of the hot topics of the college entrance examination propositions. They often use analytical geometry knowledge as a carrier, synthesis of functions, series, vectors, inequalities, triangles and other knowledge, more knowledge points involved, and the level of problem-solving ability examination The requirements are relatively high. When candidates answer questions, they often show no way to start or half abandon. In fact, such problems are always inextricably linked to “discriminative”, so the discreet application of discriminants in conic-curve problems is studied. Can better guide students to master the conic issue. First, the use of discriminant to solve the positional relationship between straight lines and conic curves