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In **cartesian coordinates** (or **rectangular coordinates**), the
``address'' of a point *P* is given by two real numbers indicating the
positions of the perpendicular projections from the point to two
fixed, perpendicular, graduated lines, called the **axes**. If one
coordinate is denoted *x* and the other *y*, the axes are called the
** x-axis** and the

**Figure 1:**
In cartesian coordinates, *P*=(4,3),
*Q*=(-1.3,2.5), *R*=(-1.5,-1.5), *S*=(3.5,-1), and
*T*=(4.5,0). The axes divide the plane into four **quadrants**:
*P* is in the first quadrant, *Q* in the second, *R* in the
third, and *S* in the fourth.
*T* is on the positive *x*-axis.

*Silvio Levy
Wed Oct 4 16:41:25 PDT 1995*

This document is excerpted from the 30th Edition of the *CRC Standard Mathematical Tables and Formulas* (CRC Press). Unauthorized duplication is forbidden.