Buy a tutorial book. When I was in the first grade, basically what the teacher said was junior high school. I almost forgot the proof you mentioned. There are many geometry problems in junior high school. I may have written a certificate. Then because of a theorem or definition, the triangle composed of three points rushed up at one point, so it rushed up at two points because then I usually draw braces to write the results obtained through different theorems and finally pass the appeal. The result of the theorem may be the answer or the formula to be proved. In short, buy a counseling book and recommend a set of books called "The Sea" to you. It is not that the tutorial book is thicker than the exercise book, but that the answers are very detailed and the answering steps are very standardized. Basically, if you understand all the above questions, you can ignore the junior high school teachers.