Conic sections are popular and familiar forms we see every day. We are interested in how to produce them using SVG.
These are the circle, ellipse, parabola, and hyperbola.
All conic curves are evolved from the geometric form called a 'circular cone'. This is produced by a straight line moving around the circumference of a circle AND always passing through a fixed point that is not in the plane of the circle.
Usually though, we only work with one half of a circular cone. It's the pointed one with a circle for the bottom.
From the side a cone looks like a triangle: Figure 1
If you look at a cone from the top, you would see a circle with a dot in the center: Figure 2
A circle is produced when the cone is sliced horizontally, or parallel with the bottom: Figure 3
The ellipse is produced when the cone is sliced at an angle that is not parallel with the slope of the cone: Figure 4
Note that the circle and ellipse are typically closed curves, but we can and do use partial arcs of them in some cases.
More Conic Sections Parabola and Hyperbola