(2) Reverse thinking. As the name implies, it is thinking in the opposite direction. Using reverse thinking to solve problems can enable students to think about problems from different angles and directions and explore solutions, thus broadening students' thinking of solving problems. This method is recommended for students to master. In junior high school mathematics, reverse thinking is a very important way of thinking, which is more obvious in the proof questions. There are few knowledge points in mathematics, and the key is how to use them. For junior high school geometry proof, the best way is to use reverse thinking. If you are in grade three, you are not good at geometry and have no idea of doing the problem, then you must pay attention to it: from now on, summarize the methods of doing the problem. Students read the stem of a question carefully and don't know where to start. I suggest you start with the conclusion. For example, there can be such a thinking process: prove that two sides are equal, as can be seen from the picture, we only need to prove that two triangles are equal; To prove the congruence of triangle, combined with the given conditions, we need to see what conditions need to be proved and how to make auxiliary lines to prove this condition. In this way, we can find a solution to the problem and then write out the process. This is a very useful method. Students must try.
(3) positive and negative combination. For topics that are difficult to separate ideas from conclusions, students can carefully analyze conclusions and known conditions. In junior high school mathematics, known conditions are usually used in the process of solving problems, so we can look for ideas from known conditions, such as giving us the midpoint of a triangle, and we must figure out whether to connect the midline or use midpoint multiplication method. Give us a trapezoid, we should think about whether to be tall, or to translate the waist, or to translate the diagonal, or to supplement the shape, and so on. The combination of positive and negative is invincible.
The key is to skillfully use and memorize the following principles in junior high school mathematical geometry proof skills.