This applet shows the TNB or Frenet reference frame. [br][br]Note that for GeoGebra, we have to write [math]\left\langle x(t), y(t), z(t) \right\rangle[/math] as [math]\left\langle f(x), g(x), h(x) \right\rangle[/math].[br][br]Slide [math]t[/math] to move the point along the curve.