2D Coordinate Geometry

2-dimensional coordinate geometry involves assigning each and every point in 2-dimensional space with coordinates which can be uniquely used to identify the point. The coordinates are measured with respect to two mutually perpendicular reference lines, known as the coordinates axes.

The coordinate axes are commonly referred to as the $x$-axis and $y$-axis. The coordinates of the points are denoted as $(a,b) ,$ where $a$ is known as the $x$-coordinate or the abscissa. It is equal to the distance of the point from the $y$-axis (or vertical axis). $b$ is known as the $y$-coordinate or the ordinate. It is equal to the distance of the point from the $x$-axis (or horizontal axis).