The law of parallelism is that the two diagonals of the sum of parallelograms are equal.
It is proved that if the sum vector of vectors A and B is C, then
C = A + B
Translate both sides of the above equation with vector a to obtain
A = C - B
Two equal parallelograms can be obtained by making parallelograms on vector c and vector b respectively. So the two diagonals are equal, which is the theorem of vector equal sum line.
The length of a vector can be expressed by the modulus of the vector, that is,
|A| = √(x^2 + y^2 + z^2)
Where A = (x, y, z) is the coordinate of the vector.
Application:
1. Using the theorem of vector equal sum line, you can find the sum vector or difference vector of any two vectors in plane or space.
2. According to the module of the vector, we can find the length of the vector, and then calculate the projection, included angle and orthogonality of the vector.
3. In mechanics, vectors can represent forces, and the resultant force and differential force of multiple forces in different directions can be solved by the theorem of equal sum line.
The more important knowledge points in high school mathematics include the following aspects:
1, trigonometric function: trigonometric function includes sine function, cosine function, tangent function, etc. It is a common knowledge point in high school mathematics. Students need to master the concept, properties, images and applications of trigonometric functions.
2. Function: In high school mathematics, function is a core concept, which requires students to master the concept, nature, image, deformation and application of basic functions.
3. Analytic geometry: Analytic geometry is one of the key and difficult points in senior high school mathematics. In the learning process, we need to master the knowledge points such as curve equation, straight line equation and plane vector.
4. Derivative and calculus: Derivative and calculus are also important contents of high school mathematics. Students need to master the definition, nature, operation and application of derivatives, as well as the basic principles and concepts of calculus.
5. Probability statistics: Probability statistics is a key content of high school mathematics. Students need to master the basic concepts, properties and operations of probability, as well as the applied knowledge of statistical data processing and chart interpretation.
6. Trigonometric function, function, analytic geometry, derivative and calculus, and probability statistics are the most important knowledge points in high school mathematics, which are not only the knowledge points required for the college entrance examination, but also the basis for subsequent college mathematics learning.