This demo includes one graphical display window that shows the curve
X(t) and the point X(t0).

The control window displays the arclength L of X(t), the area A
enclosed by X(t) if X(t) is a simple curve, and the ratio L2/4piA,
which is always greater than or equal to 1 according to the
isoperimetric inequality.

You can change t_{0} and X(t) in the control window. The
control window also includes a list of curves that you can enter for
X(t) and parameters used in defining those curves. For example, enter
cardioid(t) in the X(t) textbox to make X(t) a cardioid. Changing k
will then change the cardioid.