High school will involve a little basic advanced mathematics. Basic principles of calculus or something.

Then there is L'H?pital's law, which is not mentioned in high school textbooks, which is very helpful to solve the derivative problem.

Secondly, Taylor expansion can also solve difficult problems easily, but it is more difficult to master.

For conic curves, we can consider learning a little knowledge of parametric equations and implicit function derivatives (both of which are complicated)

You can also consider operations in the complex field.