Quadrants

In analytic geometry, one of the four regions of the plane determined by two lines, the x-axis and the y-axis. Commonly these lines are drawn perpendicular to each other, and the quadrants, or regions, they determine are numbered counterclockwise, beginning with the upper right quadrant.

In geometry, a region of a plane determined by two perpendicular radii of a circle and the circle itself. Thus two perpendicular diameters of a circle divide it into four regions, or quadrants.

A Cartesian coordinate system identifies each point uniquely on a plane, by using a pair of numerical coordinates which are the signed-distances from a given point, to two fixed perpendicular reference lines measured in the same unit of length.

An individual reference line, in this system, is called a coordinate axis or an axis. The point where the axes intersect is the origin. A point's coordinates are signed-distances, expressed in units of length, which are obtained from perpendicular projections from the axes.

One can use the same principle to specify the position of any point in three-dimensional space by three Cartesian coordinates, its signed distances to three mutually perpendicular planes

The axes of a two-dimensional Cartesian system divide the plane into four infinite regions, called quadrants, each bounded by two half-axes. These are often numbered from 1st to 4th and denoted by Roman numerals: I (where the signs of the two coordinates are (+,+), II (-,+), III (-,-), and IV (+,-). When the axes are drawn according to the mathematical custom, the numbering goes counter-clockwise starting from the upper right ("northeast") quadrant.

The two axes divide the plane into four sections called "quadrants". The quadrants are labeled with Roman numerals (not Arabic numerals), starting at the positive x-axis and going around anti-clockwise

When you get to trigonometry, this method of numbering the quadrants will make perfect sense and will be very useful.