The proportional function is a straight line, and the image must pass through a point. The symbol of k is the key, which determines the quadrant of the straight line. Negative k goes through two or four limits, X increases and Y decreases, and K remains unchanged, resulting in a primary color line, B adds up and decreases, and the image goes through three limits. Two points determine a line, and the key is the selection of coefficients.

The hyperbola of inverse proportional function can be determined by only one point. Positive k is in the range of one or three, x increases and y decreases. At any point on the image, the rectangular area remains unchanged, and the symmetry axis is the angular bisector. The order of x and y can be interchanged.

The selection of parabola of quadratic function needs three points, namely, the positive and negative opening of A, the size of C on Y axis, the simplest sign of △, the counting of intersection points on X axis, the complete calculation of food poisoning knot of B, the parabola with the same sign on the left side of A and B axis translation A unchanged, and the vertices are pulled left and right. The three forms can be transformed, and the matching mode plays the most critical role.

Similar triangles knowledge point

Test center: similar triangles's concept, the meaning of similarity ratio, and the enlargement and reduction of drawing graphics.

Assessment requirements: (1) Understand the concept of similarity; (2) Grasp the characteristics of similar figures and the significance of similarity ratio, and zoom in and out known figures as required.

Test sites: the proportion theorem of parallel lines and the related theorem of parallel lines on one side of a triangle.

Examination requirements: Use the proportional theorem of parallel lines to understand and solve some geometric proofs and geometric calculations.

Note: An edge judged to be parallel cannot be used as the corresponding line segment in the condition in proportion.

Test site: similar triangles's concept

Evaluation requirements: Based on the concept of similar triangles, master the characteristics of similar triangles and understand the definition of similar triangles.

One lap after three o'clock.

1, a circle passing through three points

Three points that are not on the same straight line determine a circle.

2. The circumscribed circle of a triangle

A circle passing through the three vertices of a triangle is called the circumscribed circle of the triangle.

3. The outer center of the triangle

The center of the circumscribed circle of a triangle is the intersection of the perpendicular lines of the three sides of the triangle, which is called the center of the triangle.

4. Quadrilateral properties of inscribed circle (judging conditions of four-point * * * circle)

Diagonal complementarity of quadrilateral inscribed in a circle.

The above are the math knowledge points from Grade One to Grade Three that I summarized for you, for reference only, and I hope it will help you.