PS: Most of these questions require you to find a functional relationship between an area and time. Common techniques are as follows
1, direct method.
2. Small area+small area or large area-small area.
3. A little more difficult will involve the knowledge of triangle similarity. Look at the ending of the 2009 senior high school entrance examination in Jilin Province.
4. Establish a plane rectangular coordinate system when there is no way out. In the coordinate system, each line segment has its corresponding analytical formula, and even the most difficult problem can be solved, but the amount of calculation is a bit large (not only the motion change problem can be established, but also the plane geometry problem can be established).
In a few provinces and cities, the final exam is plane geometry, such as Harbin, which is not simple. It's best to draw a bigger picture with a performance paper. Don't be afraid to connect auxiliary lines. Think more about similarity, congruence and four-point circle, and extend a line segment to twice the original line segment to learn from each other's strengths. Please take a look at the penultimate fill-in-the-blank questions in Harbin 2009 (possibly 20 10) and Shenzhen 2065438.
There are also some provinces and cities that combine quadratic function images with plane geometry, such as Jiangsu and Tianjin. This kind of problem has the flavor of analytic geometry in high school. You can preview the knowledge of analytic geometry in high school when you have time. Don't forget Vieta's theorem!