平面向量是高中数学的核心知识,两个向量的数量积是平面向量最重要、最活跃的内容,它的应用十分广泛,也是高考重点考查的内容.许多同学对于求解平面向量数量积的取值范围的问题有时感觉困难.本文结合一道例题来谈谈此类问题的解题思路和方法.例题如图1,△ABC是边长为 Plane vector is the core knowledge of high school mathematics, the number of two vector product is the most important planar vector, the most active content, its wide range of applications, but also the focus of the entrance examination test many students for solving the number of planar vector product The range of problems sometimes feel difficult.This article combined with a case to talk about the problem-solving ideas and methods of such problems.Examples in Figure 1, △ ABC is the side length of