The ordinate is the second component of an ordered pair. For example, if (x, y) is an ordered pair, then y is the ordinate here. An ordered pair is used to denote a point in the Cartesian plane. It is the second of the two terms (x, y) by which a point is defined, in a system of fixed Cartesian Coordinate plane. The first coordinate (x), in the plane, is called the abscissa. The cartesian system designates each point in an XY plane, uniquely, by a pair of numerical coordinates. These points are at the distances from the two fixed axes, measured in the same unit of length.
Take an example, of a point A in the cartesian plane, having coordinates (6, 9), where 9 is the ordinate and a point B, having coordinates (7, -5), where -5 is the ordinate. In case of point A, the ordinate is positive, so we will move towards a positive direction in y-axis from the origin (0, 0) at 9 equal division but in case of point B, we will move towards negative direction at 5 equal division.
The graph given below is an example of a Cartesian coordinate system, having 3 different points marked in the XY plane.
The 3 points (1, 2), (3, -3) and (-5,7) are away from the origin (0, 0). In the point (1, 2), while plotting the ordinate, two parts are covered in the positive direction of the Y-axis. Similarly, for point (3, -3) the ordinate cover three parts towards the negative direction of Y-axis, as the ordinate is negative here.
Relation of Coordinate System with the Y-axis
The ordinate depends entirely on the Y-axis. So while plotting it in a cartesian plane, we have to move along or parallel to the positive or negative direction of the Y-axis. This represents the relation between the coordinate system and the y-axis.
Abscissa and Ordinate
The distance of a point from y-axis scaled with the x-axis is called abscissa or x coordinate of the point. The distance of a point from x-axis scaled with the y-axis is called ordinate. The abscissa and ordinate all together are called coordinates.
The coordinates are written in the brackets (), where abscissa is written in the first position and then ordinate in the second position, separated by a comma. If x and y are abscissa and ordinate respectively, then the location of the point P in the cartesian plane is expressed by the ordered pair (x, y).