This demo shows some contours for the function f(r,t)= r²cos(2t). The contours consist of contour curves f(r,t) = c, and you can view them on the function graph in the "Function Graph: f(r,t)" window.

In the "Domain" window, we show the contour curves projected down into the rt-plane without actually displaying the function graph. This is called a "contour map", and it will prove to be very useful to look at in analyzing function graphs of functions f depending on more than two variables.