TRIANGLE CENTERS
Long before the first pencil and paper, some curious person drew a triangle in the sand and a line from each
vertex to the midpoint of the opposite side. Amazingly enough the three connecting lines met in a single
point - a point of concurrency. If you try it right now, the same thing
will happen, no matter what shape of triangle you start with. The special point is called the centroid of the
triangle. Think of it as the first triangle center, historically and conceptually.
Aside from the centroid, the ancient Greeks also
were fascinated by three other triangle centers: the triangle's incenter, circumcenter, and orthocenter.
Centuries passed before a
fifth triangle center surfaced: the Fermat point.
During the nineteenth century, more triangle centers entered the
literature, and then the people didn't talk much about them for a period of time.
New triangle centers are once again popping out, often with the help of
computers. In the 1980s, it seemed that all these special points shared some general properties that should form the basis for a formal definition of triangle center.
For extra credit:
(You may do as many as five different constructions – only 3 can be
classical centers – the other two must be 20th century centers.
Each completed construction (as described below) is worth 5 points. Only two
constructions can be placed in any one grade category!)
1.
Pick
a triangle center from the ones above.
2.
Open
a Word document, put your name at the top, and title your extra credit the name of the triangle center that you plan to create.
3.
In
the Word document, describe the triangle center that you will create- how it is
to be constructed, any special properties that it has, and any interesting
things about that center.
4.
Using
Geometer's Sketchpad, construct a triangle and the center that you have
chosen. When you know how to make the sketch, record a script for your
construction and save it to your disk.
5.
Copy
your triangle center construction into your Word document.
6.
At the bottom of the document
identify :
- the script's file name
- the name of the file where the actual construction can be found, and
- the grade category that you want to put the points in.
7. Hand in your print-out and your disk. |