How do you draw a polar curve?

Question

For example, r=2+cos2(thetha)

You need to plot points where theta varies from 0 to 2pi, unless you have a graphing program (which I do). Your example looks like 2 overlapping circles.

so u mean that it can't be drawn by hand?

You can draw it by hand, but you need special polar coordinate graphing paper.

Generally polar equations cannot be drawn by hand very well. The equation you asked about looks something like overlapping circles which is difficult to draw accurately free-hand. To get some idea what it looks like try calculating points at pi/6 or 30deg intervals to get an idea what the graph looks like. Then connect the points with smooth curves. It definitely helps having access to some kind of graphing application when dealing with polar coordinates.