Thursday, October 25, 2012

Slope of a Line

The line below can be changed by dragging the blue points to a different location or by dragging the entire line.  Points C and D can be moved along the line, but they cannot change the line.

  • Move C and D along the line and calculate the ratio
    m= ∆y/∆x=(y2- y1)/(x2- x1) for several different positions of the points. 
  • Show the equation of the line and look for a relationship between the coefficients of the equation and  the slope and the y-intercept of the line.

Irina Boyadzhiev, Created with GeoGebra

Download the applet

Thursday, October 18, 2012

Tessellation 2: Square, Hexagon, Triangle

The figure below shows that a plane can be tessellated using 3 regular polygons: squares, hexagons, and triangles. This is a Java Applet created using GeoGebra from - it looks like you don't have Java installed, please go to

Monday, October 8, 2012

The GeoGebra 4.2 Sneak Peek Series

I have started writing about the new features of GeoGebra 4.2 in the GeoGebra 4.2 Sneak Peek Series. The series will cover the major changes and new features of GeoGebra. As of this writing, there are already three articles in the series. I will update the series from time to time.

If all goes well, GeoGebra 4.2 will be released within the year.

The GeoGebra for iPad Kickstarter Project has reached US$10,000 but is still accepting donations. Aside from the iPad application, an Android application is also being developed.