The quantity that specifies the direction and size is called a vector. Vector, also known as vector, was originally applied to physics. Many physical quantities such as force, velocity, displacement, electric field intensity and magnetic induction intensity are vectors. Around 350 BC, Aristotle, a famous ancient Greek scholar, knew that force can be expressed as a vector, and the resultant force of two forces can be obtained through the famous parallelogram rule. The word "vector" comes from directed line segments in mechanics and analytic geometry. Use directed lines for the first time.

In mathematics, we usually use points to indicate position and rays to indicate direction. In a plane, all rays from any point can be used to represent all directions in the plane.

The representation of a vector is often represented by a directed line segment, the length of which indicates the size of the vector, and the direction indicated by the arrow indicates the direction of the vector.

Vector can also be represented by letters A (1), b, c, etc. Or use letters to indicate the starting point and ending point of the vector directed segment.

vectors

The size of, that is, the size of the vector

|a| The length (or modulus) of a vector with a length of 0 is called a zero vector, and a vector with a length equal to 1 unit length is called a unit vector.