处理三角题,解题者的思维很容易只在三角公式变来变去地打转转,于是隐入困境,其实,还可用非三角方法解三角题,这可以培养思维的灵活性.不过,用非三角方法解三角题,要注意正、余弦函数的值域,才能保证解题的正确. When dealing with triangular problems, the problem solver’s thinking is very easy to change and turn around only in the formula of the triangle, so it hides in the predicament. In fact, the triangle problem can also be solved by the non-triangular method, which can cultivate the flexibility of thinking. However, To solve a triangular problem with a non-triangular method, we must pay attention to the range of the positive and cosine functions in order to ensure the correctness of the problem.