一个三角函数问题通常含有多个角,我们可选择其中一个角或找到一个新的角作为主要的变量,称为主元,把其他角暂时看成常数或用该主元来表示,从而把问题转化为只关于该主元的问题来解决,这种方法称为主元法.使用主元法处理问题,可使解题过程程序化、解题目标明确化。 A trigonometric problem usually contains multiple corners. We can select one of the corners or find a new corner as the main variable, called the pivot element, and temporarily treat other corners as constants or use the pivotal element to represent the problem. Converted to solve only the problem of the pivot element, this method is called the pivotal element method. Using the pivotal element method to deal with the problem can make the problem-solving process procedural and the problem-solving goal clear.