Vector a? Vector b =| vector a|*| vector b|*cos, let vector a=(x 1, y 1), vector b=(x2, y2), | vector a | = √ (x12+y1)

Cross product formula:

Let vector a=(x 1, y 1), vector b=(x2, y2), ab = x1x2+y1y2 = | a || b | cos θ (θ is the angle between a and b).

Vector is not called product, it is called product of quantity. For example, a and b are called the quantitative product of a and b or point a times b.

Cross product | c | =| a× b | =| a ||| b | sin.

Vector multiplication is divided into inner product and outer product:

Inner product: ab = ab cos α, and the inner product has no direction, which is called point multiplication.

External product: a*b= buy buy, buy buy, buy buy, buy buy, buy buy, buy buy, buy buy, buy buy, buy, buy, buy, buy, buy, buy, buy, buy, buy 200, which is the difference, which is convenient for expression, so the difference is used.

In addition, the outer product can be expressed as the area of a parallelogram with side lengths A and B = the product of modules of two vectors *cos included angle = abscissa product+ordinate product.

Definition of vector:

? It is a basic concept in mathematics, physics, engineering science and many other natural sciences. Refers to a geometric object that has both size and direction and satisfies the parallelogram law.