The theorem of equal proportion is used in many places, but in senior three, you can feel that it can be used in trigonometric functions, for example, but it needs to be studied before it can be used at the right time. This theorem is generally ignored by teachers, and some teachers don't even know it, so you don't usually talk about it.

Recite the theorem on the circle again, and you can use it when you study.

Vieta theorem, when learning a function, the symmetry axis on the quadratic function δ should be combined with the image.

There are still many, I can't remember.

Helen's formula, bernhard's inequality, Cauchy's inequality, these are not only in junior high school, but teachers may not speak them. The college entrance examination can be used sometimes, so it's best to know them.

What I said may not be used at ordinary times, and I may not notice it when I study related chapters. It's for the college entrance examination.