Orienting Yourself: The Uses of Co Ordinate

To locate the position of an object or a point in a plane, we require 

two perpendicular lines — One of them is horizontal, and the 

other is vertical.

z The plane is called the cartesian plane, the coordinate plane or 

the xy-plane and the lines are called the coordinate axes.

z The horizontal line is called the x-axis and the vertical line is 

called the y-axis.

z The coordinate axes divide the plane into four parts called 

quadrants.

z The point of intersection of the axes is called the origin.

z The distance of a point from the y-axis is its x-coordinate and 

the distance of the point from the x-axis is its y-coordinate. If the 

x-coordinate of a point is x, and the y-coordinate is y, then (x, y) 

are called the coordinates of the point.

The coordinates of a point on the x-axis are of the form (x, 0), and 

those of the points on the y-axis are of the form (0, y).

z The coordinates of the origin are (0, 0).

z The coordinates of a point are of the form (+, +) in the first 

quadrant, (–, +) in the second quadrant, (–, –) in the third quadrant 

and (+, –) in the fourth quadrant.

z If x = y, then (x, y) = (y, x). If x ≠ y, then (x, y) ≠ (y, x).