Sunday, January 7, 2018

geometry - Problem with the Pythagorean theorem




The Pythagorean theorem has already been proved and it is a basic fact of math. It always works, and there are proofs of it. But I have found a problem.



Say you want to get from point A to point B.



an image




Here is a way to do it, where red is vertical movement and grey is horizontal movement.



another image



Now say you split the path up like this. Note that it is the same length, as you can see from the color of the lines:



another image again



You can continue to do this... (note that the path still continues to stay the same length):




yet another image



And if you continue forever, the path will become diagonal.



yet another image again



But now there's a problem. This is contradicting the Pythagorean theorem:



so many images!




I know the Pythagorean theorem is true and proven, so what is wrong with this series of steps that I went through?


Answer



By splitting the path you have essentially created lots of little triangles. You still need to apply Pythagoras' theorem to each one. If you do, then you will get the correct answer.


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