Pythagorean theorem defines the relationship between the 3 sides of a right angled triangle. These are the opposite side, hypotenuse side and the adjacent side.
The theorem states that the sum of the squares of the lengths of the opposite side and the adjacent side is equal to the square of the length of the hypotenuse such that mathematically,
a² + b² = c²
where a and b are the lengths of the opposite and adjacent side and c is the length of the hypotenuse