Tollorin wrote:
Depend on how are made the proofs... I was sucking in the way it was made. When the teacher had give us a optional homework on proving the pythagorean theorem (with the figure bellow), I was able to do it with algebra though.
![Image](http://www.cut-the-knot.org/pythagoras/proof31.gif)
There's a much easier proof with that picture.
Note, of course, that all four triangles are identical, so fill in "a" and "b" around the perimeter.
Now, (a+b)^2 = c^2 + 4*(1/2 * ab) (Area of whole square, expressed directly and as a sum of all its parts)
a^2 + 2ab + b^2 = c^2 + 2ab (simplify both sides)
a^2 + b^2 = c^2 (subtract 2ab from both sides)
This the way I've done it!! ! (Of course it had take me some time...) Maybe "algebra" was not the right term... Even in mathematic there is some difference in the use of the terms betwen french and english. It''s confusing...