Using Igeom to Examine Angle Relationships

I had a recent request from a grade nine math teacher who was wondering if I could suggest interactive geometry software to support the unit on circle geometry. (Unit 8 in the Pearson Math Makes Sense text).  A quick perusal of resources turned up Igeom, a free Java applet created in Brazil and available for download on the Internet.  Igeom is relatively easy to use after a bit of instruction, and it's extremely portable.  A teacher can put the applet on a network share (such as handouts) for students to access, or it's small enough that students can copy it to their home folders and run it from there.

Note that to use Igeom, you must have Java installed.  This should be the case on all our school computers, because Open Office (which is usually installed by default) depends on Java, but at home, you may first need to download and install Java to make use of Igeom.

Because of its Brazilian origins, Igeom defaults to a Portuguese interface, so it's best to run it from a batch file that switches the interface to English.  To create such a batch file:

• Place the downloaded Igeom applet into its own folder
• Start a new text document in Notepad or your favourite plain text editor (not a word processor).  
• Copy and paste the following line into the file:  java -jar iGeom.jar nome_arquivo.geo lang=en
• Save the text file into the applet's folder, but change the file extension to BAT (not TXT).
• To run the applet double-click on the batch file.
• If you move the applet to another location, do so by copying/moving the entire folder.

I've create a video tutorial on how to use Igeom to examine the relationships between inscribed and central angles within a circle.  You can view the video below, or, if you prefer a larger format, you can watch it on Youtube by clicking here.