What is the origin?

The origin is the intersection of coordinate axes.

I. Introduction

Mathematically, the origin of the number axis is 0, and the origin of the coordinate system refers to the intersection of the coordinate axes. Together with the positive direction and unit length, it is called the three elements of the number axis, and all three are indispensable. In the two-dimensional rectangular coordinate system, the coordinate of the origin is (0,0). In the three-dimensional rectangular coordinate system, the coordinate of the origin is (0,0,0).

Second, the use

The origin plays the role of reference datum in the number axis, two-dimensional and three-dimensional coordinate systems, and the coordinates of other points can be calculated according to this point. On the number axis, the origin is 0. Starting from the origin, the point (positive semi-axis) facing the positive direction on the ray corresponds to a positive number. The point (negative half axis) in the opposite direction on the ray corresponds to a negative number, and the origin corresponds to zero.

Third, the number axis

A straight line is a collection of countless points, and there are countless real numbers including positive real numbers, zero real numbers and negative real numbers. Because of their * * * nature, they use countless points on a straight line to represent real numbers. At this time, a straight line with origin, positive direction and unit length is used to represent real numbers.

When the right side is defined as the positive direction, the number represented by the upper point on the right side of two numbers on this straight line is always greater than the number represented by the upper point on the left side, positive numbers are greater than zero, and zero is greater than negative numbers. Choose an appropriate length as the unit length, and take a point every other unit length from the origin to the right on the straight line, indicating 1 unit length in turn.