一、教学内容解析本节内容选自普通高中课程标准实验教科书人教A版《数学·必修5》第一章“解三角形”第一节“正弦定理和余弦定理”.第一节约4课时,2课时通过探究证明正弦定理,应用正弦定理解三角形;2课时通过探究证明余弦定理,应用余弦定理解三角形,本节课是余弦定理的第一课时,属于定理教学课. First, the teaching content analysis This section is selected from the ordinary high school curriculum standard experimental textbook taught A version of “Mathematics Compulsory 5” the first chapter “solution triangle ” the first section “sine and cosine theorem ” first Save 4 classes, 2 classes prove the sine theorem by exploring and apply the sine theory to solve the triangle; 2 class prove the cosine theorem by exploring and apply the cosine theorem to solve the triangle. This lesson is the first class of the cosine theorem, and belongs to the theorem teaching class.