Parametric form of ellipse

The parametric form of an ellipse is given by two perpendicular vectors a and b:
r = a cos(phi) + b sin(phi)

Please enable Java for an interactive construction (with Cinderella).

The polar angle, and the half axis a and b can be changed by interactively dragging the two bright red points. Compare the animated view.

[ conics | GA with Cinderella ]

Soli Deo Gloria. Created with Cinderella by Eckhard Hitzer (Fukui).