One of the purposes of memorizing them is to form a long-term written memory of the formulas you understand in your mind, which is very helpful for future exams: many formulas and theorems may forget how they were derived after a year or two, but if they have formed a written memory, they are easy to recall and only need to be applied in the exam.

Another point is to learn more about the expressions of these formulas and theorems by reciting. This format of describing theorems in words is very common in high schools and universities. It is necessary to familiarize yourself with this format by reciting it in junior high school for later study.

Finally, understanding and induction are different. Theorem is the result of induction. In junior high school, the process of induction is generally not reflected in the process of derivation. Some well-designed questions will get wrong answers by simply applying formulas, but when they cannot be simply applied, they need to be defined by theorem expressions.

I'm too lazy to recite this theorem. When I found out, it was too late, and everyone was already sitting in the examination room.