离心率是圆锥曲线的一个重要基本量,求离心率的范围是常见的题型.这类问题往往小题精致,大题综合,数量关系隐藏的较深,对学生的思维能力和运算能力有较高的要求.求解的思路是设法建立关于a,b,c的齐次不等式,然后将其转化成关于离心率e Centrifugal rate is an important basic conic curve, the range of seeking eccentricity is a common type of question .This type of problem is often exquisite, comprehensive, the relationship between the number of hidden deeper, for students thinking and computing ability Higher requirements. The idea of ​​the solution is to try to establish a homogeneous inequality about a, b, c, and then convert it to about the eccentricity e