2. The last question in the conic curve is often very complicated, and it is difficult to get together, which makes it impossible to calculate K. At this time, the special value method can be adopted to forcibly calculate K. The process is to get together first and then calculate δ. Using the lower David theorem, it is ok to list the expressions that need to be solved.
3. There is a step in the process of proving space geometry that I really can't think of. Just write down the conditions you don't use and draw unexpected conclusions. If the first question really can't be written directly, the second question can be used directly! Students who use conventional methods suggest that a spatial coordinate system should be established at will first. If you make a mistake, you can get 2 points!
4. A new method to find dihedral angle B-OA-C in solid geometry. Using cosine theorem of trihedral angle. Let dihedral angle B-OA-C be ∠OA, ∠AOB be α, ∠BOC be β and ∠AOC be γ. This theorem is: cos ∠ OA = (cos β-cos α cos γ)/sin α sin γ. Knowing this theorem, if you encounter the problem of finding dihedral angle in solid geometry in the exam, you will come up with a set of formulas. It is not too late. Try it?
5. Mathematical (physical) linear programming problems can be solved directly without drawing.
6. The conclusion of the first question is often used in the third question, the last big question in mathematics.
7. Math (science) fill in the blanks. Drawing in proportion has a ruler, zero-based direct seconds, and the ruler is really useful.
8. When the math choice is not good, remove the maximum and minimum values and choose another one. The teacher told us! 80% of the college entrance examination questions are like this.
9. The derivative multiple-choice questions of transcendental functions can be replaced by constant functions that meet the conditions, but not by linear functions. If there are too many conditions, killing inequalities by mirror method is also a special value method mirror method ~