In fact, the design of high school textbooks has already told you this truth.

For example, 1: Why is the projective theorem in junior high school not available in senior high school textbooks? Why can't you directly write the process of using the sum and difference formula of two angles in combination with sine theorem?

Example 2:

Function: Axisymmetric function, centrosymmetric function, advanced isomorphic function of composite function.

Solving triangle: angle bisector theorem, midline length theorem.

Sequence: interval arithmetic, interval arithmetic, fixed point principle, characteristic equation method.

Vector: polarization identity, oblique coordinate system (essential basis operation).

A few examples: space cosine theorem, radius formula of arbitrary tetrahedron circumscribed sphere.

Derived topics: the exploration of necessary conditions (the essence comes from the logical chapter of the textbook for senior one, sufficiency and necessity), the famous logarithmic mean inequality, principal component replacement, etc.

Analytic geometry: the second definition of conic curve, the third definition of conic curve, focal radius formula, focal triangle area formula and chord tangent formula.

So much of the above knowledge is closely related to the college entrance examination and appears on the college entrance examination paper. The college entrance examination is required, but the high school textbooks are not introduced. Why?

Because high school textbooks require you to use the basic definitions in high school textbooks to derive the above secondary conclusions. And this basic definition to the secondary conclusion, this derivation process is actually what you need to practice repeatedly!

From the basic definition to the secondary conclusion, if you can be particularly skilled in derivation, then you can draw inferences!

Memorize the basic definition in the textbook and the derivation process from the definition in the textbook to the second conclusion.

Don't just be satisfied with reciting many secondary conclusions, it's really useless! ! ! You have to know how to write the derivation process, which is the essence of the design of college entrance examination textbooks. You have to understand the rules of the college entrance examination game. The college entrance examination itself is a game, isn't it?

When doing the brush questions, each question is pushed back to the basic definition in the book, which is called identifying test sites.

Enumeration: NMET is an in-depth understanding of definitions.

In 2020, the college entrance examination mathematics Beijing volume multiple-choice questions last multiple-choice questions 10;

10. On March 4th, 2020, 14 was the first international pi day in the world. ? God). Historically, how to find pi? ? There are many methods, similar to the secant in China's traditional mathematics. Mathematician Alkasi's method is: When is a positive integer? ? When it is large enough, calculate the inner tangent of the unit circle? ? What are the perimeters and tangents of polygons? ? The perimeter of a polygon (a regular polygon whose edges are tangent to a circle), and their arithmetic average is taken as? ? According to Al Cassie's method? ? The approximate expression of is (? )

Just look at the basic definitions of sine and tangent:

Sine: A chord with a right angle in the unit circle is called sine, BC in the figure.

Tangent line: the tangent line facing the unit circle is called tangent line, and the figure is DE.