Coordinate System and Coordinates
2.0 Rectangular cartesian co-ordinate system
2.0 Rectangular cartesian co-ordinate system
Consider a two-dimensional coordinate geometry in which two perpendicular lines ($X$-axis and $Y$-axis) are used to locate a point in the plane as shown in the figure. The intersection of $X$-axis and $Y$-axis is called the origin ($O$) having coordinates $(0,0)$.
Let us assume a point $P$ in the plane which can be represented by a unique ordered pair $(x,y)$ which are called co-ordinates of that point.
$$\begin{equation} \begin{aligned} x \to x{\text{ co - ordinate or abscissa}} \\ y \to y{\text{ co - ordinate or ordinate}} \\\end{aligned} \end{equation} $$
$X$-axis and $Y$-axis divide the plane in four regions which are called quadrants ($I,{\text{ }}II,{\text{ }}III,{\text{ }}IV$) as shown in figure $3$.
