1, the classic topic of Arrhenius circle, is the most common topic. Determine the trajectory of the moving point, construct the mother-child similar triangles coefficient to solve the line segment, and the three-point * * * line has the shortest distance.

2. fermat point problem is also the most common maximum problem. The sum of the three line segments is the shortest. Congruent triangles realizes line segment transformation (moving to the same straight line) by rotating structure. When four points are * * * circles, the sum of line segments is the shortest.

3. The Hu Bugui problem is the same common problem of line segment maximum. For the maximum value of AB+kCD, it is first required to solve the k value of one of the line segments. Similar triangles of mother and son is usually used to solve this problem for circle A, while trigonometric function is usually used to solve this problem for Hu Bugui.

4. Questions A, B and C in quadratic function. In multiple-choice questions, this is a bit difficult, and the frequency of exams is often very high, which requires proficiency.