The Cartesian Coordinate Plane

Two real number lines constructed to perpendicular to each other, one horizontal and one vertical, form a coordinate plane, otherwise known as Cartesian Plane. It was name after Rene Descartes, a French philosopher and mathematician who introduced it in 1637.

The horizontal line is the x-axis and the vertical one is the y-axis. They intersect at a point called the origin, with corresponding ordered pair of numbers which is (0,0). The first number in the ordered pair is the x-coordinate or abcissa and the second number in the y-coordinate or ordinate. Thus, every point in the plane has corresponding ordered pair of number (x,y). The axes divide the coordinate plane into four regions called quadrant labeled I, II, III, and IV.

In plotting of points, the abcissa tells how many units to the right or to the left of the origin we should go and the ordinate tells how many units above or below x-axis the point is.