The window "Curve, T(t0), and U(t0)" displays the curve given by X(t) (which you may alter in the appropriate textbox in the control window), the point X(t0), and the unit tangent and unit normal vectors T(t0) and U(t0) with X(t0) as their base.

The window "T(t) and U(t)" displays the unit tangent and unit normal vectors with their base at the origin and the unit circle on which the heads of those vectors must lie.

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 tangent and normal vectors.