1, familiar with the right angle of a right triangle, the waist and angle of an isosceles triangle, and the symmetry of a circle. According to the special properties of graphics, find suitable objects to discuss and solve one by one. When discussing the existence of isosceles triangle or right triangle, we must follow certain principles, do not omit them, and finally synthesize them.

2. The location of the discussion point. Be sure to see clearly the range of the point, whether it is on a straight line or on a ray or line segment.

3. The correspondence of graphs mostly involves congruence or similarity of triangles, and the possible correspondence of diagonal and edge is discussed in classification.

4. If there are absolute values and squares in algebraic deformation, we should pay attention to the selection of open-close symbols.

5. The value or range of the inspection point. This part mainly examines the classification of the range of independent variables, and pays great attention to the nature, conditions and scope of the theorem in solving problems.

6. If there is an intersection between the function image and the coordinate axis in the function topic, it must be discussed that this intersection point is the intersection point with which half axis of which coordinate axis.

7. When the motion mode changes (for example, moving from one line segment to another), the written function should be discussed in sections.