How did pythagorus formulate the rule c2 equals a2 plus b2?

Answer 1

It's Pythagoras, actually.

How did he formulate it? Something like this:

'The square of the hypotenuse of a right triangle is equal to the sum of the squares of the other two legs.'

But he said it in Greek, naturally.

Several proofs of this world-shaking proposition are found in plane geometry, and it would be worth your while to investigate them.