## Saturday, October 29, 2011

### GeoGebra 4.0 now available

This is a repost from Math and Multimedia, my main blog.
The long awaited  GeoGebra 4.0 is now available online. The Webstart files and Applet Start can be are fully functional.  Hopefully the offline installers will be available soon.
Some of the new features according to the website (haven’t explored all of them yet) are the following:
• GeoGebraTube: easily share worksheets online (see “File” menu)
• User interface: drag & drop, style bar, perspectives, accessibility
• New tools: data analysis, chart dialog, probability calculator, function inspector
• Copy & Paste, two Graphics views
• Inequalities and implicit equations
• Improved text tool, better equation displaying
• Filling options with hatching and images
• Animation of points on lines, dynamic limits for sliders & axes
• Buttons, input boxes, scripting
• Export to animated GIF
• 50 languages
To know more about the other features, go to the GeoGebra 4.0 Release Notes and the updated GeoGebra Manual. The GeoGebra Prim, the version for younger students is also now available.
I will be revising my GeoGebra tutorials soon to make them compatible with the new version.

## Tuesday, October 25, 2011

### Blanchet Theorem

In triangle ABC, Point E is an arbitrary point on altitude AD. Move point A, B, C or E and observe what happens.
This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

## Thursday, October 20, 2011

### Copying a Segment

Move the cursor slider to the right by interval 1 to copy segment AB. Can you see why AB is congruent to CD? Justify your answer.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)
The construction above is a simulation of the compass and straightedge construction on how to copy a line segment.

## Monday, October 17, 2011

### Point inside an equilateral triangle

ABC is an equilateral triangle. Point D is a point in the same plane and three segments are connected to it where each segment is perpendicular to a side of the triangle as shown.

This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

1.) Move A or B to choose the size of the equilateral triangle.
2.) Move point D. What do you observe.
3.) Repeat 1 and 2 several times. Is your observation still the same?
4.) Make a conjecture about your observation and try to see if you can prove it.

## Monday, October 10, 2011

### Circumference of a circle

Move the slider to the extreme right and observe what happens.

Sorry, the GeoGebra Applet could not be started. Please make sure that Java 1.4.2 (or later) is installed and active in your browser (Click here to install Java now)

This is a demonstration that the circumference of a circle with radius 1 is equal to 2*pi or approximately 6.28.

More than 50 GeoGebra Tutorials at Math and Multimedia

## Thursday, October 6, 2011

### Constructing congruent triangles

Move the slider to the right one step at a time and observe what happens.

1.) After the construction, move any of the vertices of triangle ABC. What do you observe?
2.) How is the construction similar to the manual compass and straightedge construction?
3.) Which of the congruence postulates of triangles does the construction show?

This is a Java Applet created using GeoGebra from www.geogebra.org - it looks like you don't have Java installed, please go to www.java.com

The construction above is a simulation of constructing a triangle congruent to a given triangle using compass and straightedge.