近几年高考降低了对三角变换的考查要求,而加强了对三角函数的图象与性质的考查.函数的性质是研究函数的一个重要内容,而三角函数图象又是研究三角函数性质的有力工具,因此,在研究三角函数时要充分运用数形结合的思想,把图象与性质结合起来,即利用图象的直观性得出函数的性质, In recent years, college entrance examination to reduce the requirements of the triangular transformation test, and to strengthen the image of the trigonometric function and the nature of the test. The nature of the function is an important part of the research function, and trigonometric function is the nature of trigonometric functions Powerful tools, therefore, in the study of trigonometric functions should make full use of the idea of ​​digital combination, the image and the nature of the combination of the use of the image of the intuitive nature of the function,