this is a very vague question if you are looking for the his

this is a very vague question, if you are looking for the history of the pythagorean theorem, then perhaps wikipedia might be useful to you.
have referenced a link to the wikipedia page on pythagorean theorem

Solution

We\'ll start from the fact that if we\'ll construct a square whose one side lies on the hypotenuse of a right angle triangle, we\'ll notice that the area of this square is equal to the sum of areas of the squares whose one side lies on each leg of this triangle.

If we\'ll note the length of hypotenuse as z, the area of the square is [z^(2)] .

If the lengths of the legs are x and y, therefore the areas of the squares are [x^(2)] and [y^(2)] .

Therefore, according to Pyhtagorean theorem, we\'ll get:

[x^(2)] + [y^(2)] = [z^(2)]