1, congruent triangles: congruent triangles's judgment and nature are the key points. We need to master and flexibly use congruent triangles's judgment and proof of congruence, and master several congruence models.

2. isosceles triangle: the nature and judgment of isosceles triangle is the focus of learning, especially the three-line integration of isosceles triangle. In addition, learning isosceles triangle needs to master some commonly used mathematical ideas, such as classification discussion ideas, equation ideas, and common construction methods of isosceles triangle.

3. equilateral triangle: equilateral triangle is a special isosceles triangle, which has all the properties of isosceles triangle and some special properties. It is often combined with the fact that the right angle side facing 30 degrees in a right triangle is half of the hypotenuse.

4. Right triangle: the nature and judgment of right triangle, isosceles right triangle and 30-degree right triangle are the focus of learning, and there are many property theorems, which need to be mastered and applied systematically.

5. The properties of the midline of the line segment and the midline of the line segment are the key points. Only by mastering its characteristics and basic problem-solving ideas and methods can we solve the most difficult problem of drinking horses.

6. Angular bisector. The nature of angular bisector is the focus of learning. When you see an angular bisector, you need to think of equal angular segments and vertical segments. Although the bisector is simple, there are many auxiliary lines and models related to the bisector, so you need to be familiar with the common models and application methods.