解决数量积问题,一是直接用定义求解;二是选择恰当的基底,将所要研究的向量用基底表示出来,通过基底的运算来解决问题,即基底法;三是建立直角坐标系,用坐标来表示向量,尤其是在出现中点或垂直关系时,这种转化会特别有效,在解题中要善于把握与领会.对于“三法”的选择,应具体问题具体分析. Solve the problem of the number of products, one is to use the definition of the direct solution; the second is to select the appropriate substrate, the vector to be studied with the substrate expressed by the operation of the substrate to solve the problem, that is, the substrate method; third is to create a rectangular coordinate system, To express the vector, especially in the mid-point or vertical relationship, this transformation will be particularly effective in the problem-solving should be good at grasping and understanding of the The choice of “three laws ” should be specific analysis of specific issues.