The Cartesian coordinate system in two dimensions (also called a rectangular coordinate system) is defined by an ordered pair of perpendicular lines (axes), a single unit of length for both axes and an orientation for each axis.
The lines are commonly referred to as the x- and y-axes where the x-axis is horizontal and the y-axis is vertical. The point where the axes meet is taken as the origin for both, thus turning each axis into a number line.
For a given point P, a line is drawn through P perpendicular to the x-axis to meet it at X and a second line is drawn through P perpendicular to the y-axis to meet it at Y. The coordinates of P are then X and Y interpreted as numbers x and y on the corresponding number lines. The coordinates are written as an ordered pair (x,y).
The lines are commonly referred to as the x- and y-axes where the x-axis is horizontal and the y-axis is vertical. The point where the axes meet is taken as the origin for both, thus turning each axis into a number line.
For a given point P, a line is drawn through P perpendicular to the x-axis to meet it at X and a second line is drawn through P perpendicular to the y-axis to meet it at Y. The coordinates of P are then X and Y interpreted as numbers x and y on the corresponding number lines. The coordinates are written as an ordered pair (x,y).