Usually, the two number axes are placed in horizontal and vertical positions respectively, and the right and upward directions are the positive directions of the two number axes respectively. The horizontal axis is called X axis or horizontal axis, the vertical axis is called Y axis or vertical axis, and the X axis and Y axis are collectively called coordinate axes.
The ordinate of this point on the horizontal axis is zero; The abscissa of a point on the vertical axis is zero. In any two points, if the abscissas of the two points are the same, the connecting line of the two points is parallel to the longitudinal axis (the abscissas of the two points are not zero); If the vertical coordinates of two points are the same, the connecting line of the two points is parallel to the horizontal axis (the vertical coordinates of the two points are not zero).
In the plane rectangular coordinate system, the vertical number axis is represented, the arrow is upward (that is, the Y axis, and the real number on the Y axis represents the ordinate), and the dependent variable is represented in the function. On the contrary, the x-axis represents an independent variable.
Extended data
In the rectangular coordinate system, for any point on the plane, there is a unique ordered number pair (that is, the coordinate of the point) corresponding to it; Conversely, for any ordered number pair, there is a unique point on the plane corresponding to it.
For any point C on the plane, the intersection point C is perpendicular to the X-axis and Y-axis respectively, and the corresponding points A and B perpendicular to the X-axis and Y-axis are called the abscissa and ordinate of the point C respectively, and the ordered pair (A, B) is called the coordinate of the point C. A point is in different quadrants or coordinate axes, and the coordinates of the point are different.
Coordinate characteristics of special position points:
1. The ordinate of this point on the horizontal axis is zero; The abscissa of a point on the vertical axis is zero.
2. If the abscissas of any two points are the same, the connecting line of the two points is parallel to the longitudinal axis (the abscissas of the two points are not zero); If the vertical coordinates of two points are the same, the connecting line of the two points is parallel to the horizontal axis (the vertical coordinates of the two points are not zero).
3. Distance from point to axis and origin:
The distance from the point to the X axis is | y | The distance from the point to the Y axis is | x | The distance from the point to the origin is the square of x plus the square root of y.
Baidu Encyclopedia-Vertical Axis (Mathematical Term)