The Excess (or Missing) Area

Click the Play button at the bottom-left of the applet to animate. What do you observe?




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)

1. Click the Pause button and refresh your browser.
2. What is the area of the square made up of the two triangles and two trapezoids? 
3. Check the Assemble Manually check box to show the slider. 
4. Set the slider and to 90, and then a to 0 and e to 8. What is the area of the rectangle?
5. Can you explain why there is an excess area?  

Downloadable Applet to follow