2004年高考数学全国卷2理科第21题是一道综合性较强的题,它以解析几何为背景,结合了向量、函数这两部分知识,题中不乏各种变量之间的转换,挖掘题目中的隐含条件是解决该题的关键之一.本题的入口很宽,从 The 2004 National Mathematics for College Entrance Examination Volume 2 is a comprehensive problem. It uses analytic geometry as the background, combines the knowledge of the two parts of vector and function, and there are no shortages of conversions between various variables. The implied condition in the question is one of the keys to solving the problem. The entry of this question is very wide, from