正余弦定理是三角函数的重要内容,也是高考经常考查的知识点,有时变形的技巧非常强,因此不少学生对稍难一点的题目常常感到无从下手,本文给大家介绍一些使用正、余弦定理的常用技巧.一、实施边角互化例1在△ABC中,角A、B、C所对的边分别为a、b、c,已知c=1,C=120°求a+b的最大值. The sine cosine theorem is an important part of the trigonometric functions, but also the college entrance examination often check the knowledge points, and sometimes the deformation of the skills is very strong, so many students often feel difficult to start with the problem, this article to introduce some use positive and cosine theorem Of the commonly used techniques. First, the implementation of each corner of the mutual 1 In △ ABC, the angles A, B, C on the sides were a, b, c, known c = 1, C = 120 ° seeking a + b The maximum value.