Figure 6.7. A two-dimensional coordinate systemInathree-dimensionalcoordinatesystem,there’salsoaZ-axis.Thisaxisisperpen-
diculartoboththeXandYaxes,aswellasthescreen(seeFigure6.8).Thepoint
atwhichtheZ-axiscrossestheXandYaxesisalsoknownastheorigin.Itscoordin-
atesare(0,0,0).232 CSS Master