One window displays the graph of X(t) (which you can alter in the appropriately labeled textbox), the point X(t

The other window displays the unit tangent vector T(t

The control window lists various functions and parameters used in defining those functions. To use one of those functions as X(t), type the function name in the X(t) textbox (e.g., type "cardioid(t)" to make X(t) a cardioid).

Change the value of t

As in earlier demos, there are "Show entire curve", "Show position vector X(t0)" and "Show Color Spectrum" options. "Show Color Spectrum" also colors the unit tangent vector.