The sum of squares of the side lengths of 2 legs of a right triangle will equal to the square of the side length of the hypotenuse.
i.e.: \(a^2 + b^2 = c^2\)
where a and b are the lengths of the 2 legs and c is the length of hypotenuse.
Any right triangles satisfies this Theorem.
wiki said : In mathematics, the Pythagorean theorem, also known as Pythagoras's theorem, is a fundamental relation in Euclidean geometry among the three sides of a right triangle. It states that the square of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the other two sides.