Chapter-Coordinate Geometry.

Chapter-Coordinate Geometry.

1. A number line can be used to represent a number or solution of an equation that only has one variable. It is sufficient to describe the solution of one-valued equations because they all are singledimensional. But as the number of variables in an equation increases, it is not enough. For example, when the number of variables in an equation becomes two, there will be pair of numbers as a solution.

2. Cartesian Plane: A Cartesian plane is defined by two perpendicular number lines, X and Y. It extends to infinity in both directions. It has a centre usually denoted by O. The horizontal line is called X-axis while the vertical line is called Y-axis.

   • The system which we have described to label points in a plane is also known as the Cartesian System. It was first described by a French mathematician named Rene Descartes in the 17th century. The word Cartesian is derived from Descartes.
     • We have seen that two perpendicular number lines X and Y are required for the Cartesian System.
       • The intersection point of the axes is the zero of the Cartesian System. This point will generally be denoted by O (also known as origin).