After the rectangular coordinate system is established, the coordinate plane is divided into four parts, I, II, III and IV, which are called the first quadrant, the second quadrant, the third quadrant and the fourth quadrant respectively.

The points on the first quadrant have positive abscissa and positive ordinate;

The point on the second quadrant has negative abscissa and positive ordinate;

The point on the third quadrant has negative abscissa and negative ordinate;

The point on the fourth quadrant has a positive abscissa and a negative ordinate.

Extended data

The establishment of rectangular coordinate system has built a bridge between algebra and geometry, so that geometric concepts can be expressed in numbers and geometric figures can also be expressed in algebraic form. On the basis of Cartesian coordinate system, Descartes founded analytic geometry, a branch of mathematics that studies geometric figures by algebraic method.

If the geometric figure is regarded as the trajectory of a moving point, it can be regarded as composed of points with certain * * * characteristics. For example, a circle can be regarded as the locus of points with the same distance from a moving point to a fixed point. If the point is regarded as the basic element of geometric figure and the number is regarded as the solution of equation, algebra and geometry will be combined into one.

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