## Tuesday, January 26, 2010

### Math Forum Project: Conic Sections

My January Project is up.

This is a straight-up geeky math project (geek being a complimetary term these days). You start by building a cone, then use SketchUp's Section Plane tool to create four different conic curves: circle, ellipse, hyperbola, parabola.

This project has a Teacher Version and a Student Version. If the students doing this project also know about curve equations, the Teacher Version has some info about verifying equations by getting various point coordinates.

I'm guessing this is definitely NOT something the SketchUp creators had in mind when they created SketchUp, but it's awesome for math-types!

If this sounds familiar, maybe it's because you've seen my video on this topic (which I see has gotten over 2,000 views!)

Anyone can design anything in 3D! www.3dvinci.net

Guzman said...

Sorry to point it out but in the video after 3:36 there's a huge math error.
You have an ellipse and you say "click a point anywhere and move the mouse [and the section plane] until the section plane is entirely within the cone. This 2D object is a parabola".

NO: that's another ellipse (part of an ellipse but still an ellipse).

To obtain a parabola the section plane must be parallel to a generatrix of the cone. (a generatrix is any straight line that belongs to the cone).

Bonnie Roskes said...

Yes, and I had forgotten the incorrect info was in the video I made a while ago. But the math forum project has the correct mathematical info - you create a section plane along one of the conic segments, therefore parallel the slope of the cone. Thanks for the comment ;-)

Anonymous said...

Don't stop posting such articles. I like to read stories like that. BTW add some pics :)
BlindSniper