# When looking at a cartesian graph

1. ### evilpostingmong

341
should every whole number that curve x crosses be taken into consideration when
constructing a polar graph? For example, when y=1 is crossed, should the radius be drawn
on the polar graph if the x value is not an exact, uh, pi number (for example instead
of .77 which is pi/4 the x value that curve x crosses 1 is at .88 or something like that)
To see what I mean, graph 3cosx and look where y=2 is crossed (at x=.84). Should I ignore this point?

Last edited: Jun 11, 2008
2. ### HallsofIvy

41,255
Staff Emeritus
?? I have no idea what you are talking about. To perfectly graph a function, you have to take every number into account, not just whole numbers! To approximately graph a function, you need to decide how accurate you want to be as opposed to how much work you want to do. The only reason for using "pi numbers" (by which I take it you mean simple fractions of pi) is that they are easy- the same reason you might use whole numbers for Cartesian graphs. There is no "mathematical" rule.