一、理解并识记定理、推论●●●●●●一个定理:三角形内角和定理——三角形三个内角的和等于180°.三个推论:1.直角三角形的两个锐角互余.2.三角形的一个外角等于和它不相邻的两个内角的和.3.三角形的一个外角大于任何一个和它不相邻的内角.二、归纳题型、掌握解法●●●●● First, understand and memorize theorems and inferences ●●●●●● A theorem: triangle internal angle and theorem—The sum of the triangle’s three internal angles is equal to 180°. Three inferences: 1. Two acute angles of right triangles. An outer angle of a triangle is equal to the sum of the two inner angles that are not adjacent to it. 3. An outer corner of a triangle is larger than any inner corner that is not adjacent to it. 2. Inductive question type, mastering the solution ●●●●●