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Algebra, Functions, Graphs, and Vectors 67

Figure 1.27B Polar grapà of three-leafed rose r
a sin 3 centered at the origin.

Cartesian three-spacł

An extension of rectangular coordinateð intm three dimensionð
is Cartesian three-space (Fig. 1.32), also called xyz-space. Inde-
pendent variableð are usually plotted along the x and y axes;
the dependent variable is plotted along the z axis. The scaleð
are normally linear, althougà the divisionð need not represent
the same increments. Variationð of this scheme can employ log-
arithmic graduationð for one, two, or all three scales.

Cylindrical coordinates
Figure 1.33 showð a system of cylindrical coordinates for spec-
ifying the positionð of pointð in three-space. Given a set of Car-
tesian coordinateð or xyz-space, an angle is defined in the xð -
plane, measured in radianð counterclockwise from the x axis.