离心率是描述圆锥曲线性质的一个重要概念.离心率范围的考查,频见全国各地考题和各种资料中.由于范围的确定涉及到代数、几何、三角等多方面知识的综合运用,所以也是一个难点.突破这个难点的关键是什么呢?是准确建立不等关系,如何建立不等关系?一种情况是问题中明确给了不等关系;另一种情况是没给但需要挖掘隐藏不等关系.下面通过实例谈一谈这类问题的几个具体求解策略.一、利用条件中已知的不等关系建立e的不等式求离心率 Centrifugal rate is an important concept to describe the nature of the conic curve .Consideration of the range of centrifugal frequency, frequent examination questions and a variety of information throughout the country .As the scope of the determination involves the algebra, geometry, triangle and other aspects of the comprehensive utilization of knowledge, so is A difficult point. What is the key to break through this difficult point? Is to accurately establish unequal relations, how to establish unequal relations? A situation is unequivocally affirmed in the problem; the other is not to but need to dig hidden And so on.Further talk about several specific solution strategies of such problems through examples.First, the use of conditions known inequalities to establish inequalities to find eccentricity