Wednesday, July 27, 2011

Quadrilateral Diagnosis

I was inspired to do this by the neat quadrilateral hierarchy sketch shared this morning on Twitter.  But I got wishing they had made the types accurate - that you could only make squares in the square spot. And that their hierarchy used the inclusive definition of trapezoid. (Pet peeve of mine.)  Then I thought what if the types lit up when you make the shape?  That led to the sketch pictured below, available as a ggb file (EDIT: in GGB 4!) or as a webpage.

When I included it as an applet here, it just didn't work as smoothly as it does over at the geogebra hosting, or by displaying the file directly in a browser.

It was very fun figuring out the conditional tags to make the names show up.  I think I've covered most of the corner cases.  Figuring out a way to do convex/concave and quadrilateral or not

It was quite handy knowing multiple definitions of each type, which me wonder about a scaled down version of this as a problem to assign to students.

Where do you stand on the trapezoid definition? Is a parallelogram a trapezoid? (I say yes!)


  1. I believe the state of Ohio considers a trapezoid to have exactly one pair of parallel sides, so that rules out parallelograms. But things are much more fun with you allow trapezoids to be inclusive.

    You might like this one. Click on the reset button to create a new quadrilateral.

  2. If a square is a rectangle, Ohio, then ...

    The poorly drawn sketch is a great idea, well executed and cute. Thanks!