The Conic Sections


Henri Picciotto

The conic sections have become a smaller and smaller part of high school math in the U.S. Nevertheless, they are interesting, and the advent of geometric construction software has made them more accessible. I share a fair amount of possibly useful materials about them on this site.

One conic section that's not going anywhere is the parabola. On my Parabolas and Quadratics page, I have links to much curriculum, ranging from Algebra 1 to "Teachers' Mathematics." The emphasis there is mostly on algebra. On this page, I mostly link to the geometry of the conic sections.

Geometry of the Parabola
In two dimensions (definition, construction, reflection property, all parabolas are similar)
In three dimensions (the parabola really is a conic section!)
Parabola Similarity (worksheet, using GeoGebra)
Geometry of the Ellipse
In two dimensions (two definitions, constructions, reflection property)
In three dimensions (slicing a cone or a cylinder)
Algebra connection (worksheet)

Paper-folding Conics (hands-on lab by Rachel Chou)

A related problem (surprisingly): Soccer Angles

Another surprise: the function diagram for `y=1/x`.