A Visual Proof of the Pythagorean Theorem

Move point E to determine the shape of the triangles, and then move slider α to the extreme right.
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
Guillermo Bautista , September 11, 2012, Created with GeoGebra


  1. What is the relationship among the areas of squares with side lengths a, b, and c
  2. What equation describes the relationship among the areas of the three squares? 
  3. Prove that the green quadrilateral inside the large when  α is  90° is a square

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