The position of each point of the plane is determined with reference to the rectangular axes by means of a pair of numbers called co-ordinates which are distances of the point from the respective axes. The distance of the point from the y-axis is called the x-coordinate or abscissa and the distance of the point from the x-axis is called y-coordinate or ordinate. The position of point P in the plane with respect to the co-ordinate axes is represented by the ordered pair (x, y), where x is abscissa and y is the ordinate.
• Co-ordinate of the origin are (0, 0).
• The co-ordinates of any point on the x-axis are (x, 0) and the co-ordinates of any point of the y-axis are (0, y)