I'm in the math department. The main function of advanced geometry for elementary geometry, I think, is to provide another way of thinking and key points for the proof of * * * line points and * * * line points. Generally speaking, there are not many contents and theorems of higher geometry, but the narrative is long, so we must see the conditions clearly when using it. The content of elementary geometry is mostly used in middle school mathematics competitions, and the theorems in mathematics textbooks are not enough, so we have to learn many theorems. I don't know if you have learned the elementary geometry of the competition, which is more useful. For example, it is difficult to find dihedral angle in high school mathematics, which is often not found, but there is a theorem in elementary geometry that can solve many such difficult dihedral angle problems.