What is Pythagoras thesis?

Answer 1

I have attached a link of the first hit on Google. I don't know how trustworthy it is but anyway (because I'm not sure if you meant theorem, and also it would be a misinterpretation of the word thesis, i.e. true and proven).

Pythagoras' Theorem on the other hand is that with a right angled triangle, the lengths of the two sides that make the right angle squared and added together gives the square of the length of the third side (opposite the right angle)