What is Pythagoras' Theorem and the Rules Surrounding it?

The two sides besides the hypotenuse(the longest side) squared adds to the hypotenuse squared.

Pythagorean Theorem:

In any right triangle, i.e., a triangle which exhibits one angle with a measurement of 90 degrees, the sum of the squares of the measurements of the "legs" of the triangle (sides opposite from the two acute angles) is equal to the square of the measurement of the "hypotenuse" (side opposite from the right angle).

Or:

a^2 + b^2 = c^2

The sum of the squares of the sides of a right angled triangle is equal to the square of the hypotenuse (The longest side).

The triangle must have one right angle (90 degrees)

The sum of the 3 inner angles (The angle between sides) of a triangle will add up to 180 degrees.

A squared + B squared = C squared

The square of one leg of a right triangle plus the square of the other leg of a right triangle equals the square of the hypotonuese.

a^2+b^2 = c^2, its a rule for figuring out triangles

I'm not sure about surrounding rules