平面向量引入中学数学，极大地丰富了中学数学的内容，也为解决数学问题提供了一种全新的方法—向量法。——向量的数量积公式·ab＝｜a｜｜b｜cosθ，其结构简单，内涵丰富，运用它处理有关向量夹角的大小、参数的取值、函数的最值、轨迹方程等问题，简洁明快，颇具特色。现举 The introduction of middle school mathematics into the plane vector greatly enriches the content of middle school mathematics, and it also provides a completely new method for solving mathematics problems - the vector method. ——The quantity product formula of vector ·ab=|a||b|cosθ. Its structure is simple and rich in content. It is used to deal with the problems such as the size of the included angle of the vector, the value of the parameter, the value of the function, the trajectory equation, etc. Simple and lively, quite distinctive. Now