必修五第一章《解三角形》是在初中学习了直角三角形边角关系和高中必修四学习了三角函数的基础上,进一步研究斜三角形中边与角的关系——正弦定理、余弦定理.这章以这两个定理为主体,进行解三角形的训练.在对本章进行教学与反思后,笔者发现这两个定理只是在研究三角形边角关系的基础上开 Compulsory fifth chapter first “solution triangle” is learned in the junior high school triangle corner relationship and the high school compulsory four learned trigonometric functions based on the further study of the relationship between the triangle and the angle triangle - sine and cosine theorem. The chapter takes these two theorems as the main body to carry out the solution of the triangle training.After teaching and reflection on this chapter, the author finds that these two theorems only open on the basis of studying the triangle corner relations