Drawing parabolas according to US Patent 5870830.

To adjust angles α and θ for each parabola.

- α angle between the orange axis and the plane of paper.

- θ: angle between the orange axis and the green arm.

α is equal to θ for parabola drawing.

The green arm rotates around the orange axis to create a cone.

Its intersection curve with the plane of paper is a parabola.