Symmetry of (1) circle

1, the axis symmetry of the circle

A circle is an axisymmetric figure, and every straight line passing through the center of the circle is its axis of symmetry.

2. The center of the circle is symmetrical

A circle is a central symmetrical figure with the center of the circle as the symmetrical center.

(2) The concept and nature of basic function.

1 and function y=-8x are linear functions.

2. The function y=4x+ 1 is a proportional function.

3. This function is an inverse proportional function.

4. The opening of parabola y=-3(x-2)2-5 is downward.

5. The symmetry axis of parabola y=4(x-3)2- 10 is x=3.

6. The vertex coordinate of parabola is (1, 2).

7. The image of the inverse proportional function is in the first and third quadrants.

(3) Common testing methods for quadratic equations with one variable.

1. Investigate the relationship between the roots and coefficients of a quadratic equation (Vieta Theorem): This kind of topic has the characteristics of strong regularity in solving problems and flexible topic setting, so it has always attracted proposers. Major inspection

① Find roots and coefficients, and explore relevant laws.

(2) Given two or one to construct a quadratic equation, such topics are generally open-ended.

2. Do the problem at the intersection of quadratic equation, geometric problem and function problem. (Geometric problem: The relationship between figures and numbers is mainly hidden in figures and represented by figures. This kind of figure mainly includes triangle, quadrilateral, circle and so on. , which involves triangle trilateral relations, triangle congruence, area calculation, volume calculation, Pythagorean theorem and so on. );

3. Establish a quadratic equation with one variable to solve practical problems, with real life as the background and a wide range of propositions. A common problem is the growth rate.

(4) Mean, median and mode of data

1, data 13, 10,12,8,7, the average value is 10.

2. The pattern of data 3, 4, 2, 4, 4 is 4.

3. The median of data 1, 2,3,4,5 is 3.

(5) Special trigonometric function values

1, cos30 = root number 3/2.

2、sin260 +cos260 = 1 .

3、2sin30 +tan45 =2 .

4、tan45 = 1 .

5、cos60 +sin30 = 1 .

Extended data

Summary of Mathematics Learning Methods in Grade Three

Prepare carefully before class. The purpose of preview is to listen to the teacher better. Through preview, the mastery level should reach 80%. Listen to the teacher answer these questions with questions that you don't understand in the preview. Preview can also improve the overall class efficiency. Specific preview method: finish the topics in the book and draw the knowledge points. The whole process lasts about 15-20 minutes. If time permits, you can also finish your homework.

Combine learning with application in math class. It's no use just listening in math class. When the teacher asks the students to do calculations on the blackboard, they should also practice on the draft paper. You must ask questions you don't understand, and you can't help but ask for answers, otherwise you may not do it when you encounter similar problems in the exam. When listening to the teacher's lecture, you must concentrate on the details, otherwise, "the embankment of a thousand miles will collapse in the ant nest."

Review in time after class. After finishing your homework, sort out what the teacher said that day, and you can do extracurricular problems for about 25 minutes. You can choose the extracurricular books that suit you according to your own needs. The content of the extracurricular problem is probably today's class.