The coordinate plane is a plane determined by two perpendicular lines, the
x-axis and the
y-axis. The
x-axis is the horizontal axis, and the
y-axisis the vertical axis. Every point in the plane can be stated by a pairof coordinates that express the location of the point in terms of thetwo axes. The intersection of the
x- and
y-axes is designated as the origin, and its point is (0, 0).
As you can see from the figure, each of the points on the coordinate plane is expressed by a pair of coordinates: (
x,
y). The first coordinate in a coordinate pair is called the
x-coordinate. The
x-coordinate is the point’s location along the
x-axis and can be determined by the point’s distance from the
y-axis (where
x = 0). If the point is to the right of the
y-axis, its
x-coordinate is positive, and if the point is to the left of the
y-axis, its
x-coordinate is negative. The second coordinate in a coordinate pair is the
y-coordinate. The
y-coordinate of a point is its location along the
y-axis and can be calculated as the distance from that point to the
x-axis. If the point is above the
x-axis, its
y-coordinate is positive, and if the point is below the
x-axis, its
y-coordinate is negative.
The Quadrants
The coordinate plane is divided into fourquadrants. Each quadrant is a specific region in the coordinate plane.The region in which
x > 0 and
y > 0 is Quadrant I. The region in which
x < 0 and
y > 0 is Quadrant II. The region in which
x < 0 and
y < 0 is Quadrant III. The region in which
x > 0 and
y < 0 is Quadrant IV.
For example, the point (4, –2) lies in quadrant IV, with an
x-coordinate that is 4 units to the right of the
y-axis and a
y-coordinate that is 2 units below the
x-axis.This is how the coordinates of a point specify its exact location. Thecoordinates of the origin are, by definition, (0, 0).
