在解析几何中 ,经常会遇到如何确立参数变化范围的问题 .此类问题也是近年高考的热点 ,而多数学生面对问题中的有关量 ,不知如何挖掘它们之间的关系 .本文通过几例谈一下这类问题的几种求法 .一、利用曲线范围我们在研究圆锥曲线的性质时 ,已经知道了曲线的范围 .我们可以通过 In analytical geometry, we often encounter the problem of how to establish the scope of parameter changes. Such problems are also hot topics in recent college entrance examinations, and most students face the amount of related issues, I do not know how to tap the relationship between them. Talk about several approaches to this type of problem. First, use the curve range. When we study the properties of conic curves, we already know the scope of the curve. We can