Because Shanghai's mathematics textbooks and junior high school mathematics syllabus require testing vectors, students in Shanghai should be able to perform linear operations on vectors. It is suggested that the subject buy the book "Plane Vector and Geometry" to read and improve his level.

If you want to use it in the topic, you can use it to prove parallelism. First of all, through a lot of operations, we get a = KB (neither a nor b is a zero vector) (the vector can be represented by bold lowercase letters, where k is a real number). If k is not equal to 0, then a//b, so the two line segments are parallel. Of course, this will also be trained in high school.

However, it is still recommended to compare the similar triangles and triangle in the dead beat. What if the teacher can't read deduction?