The simplest way to prove the Pythagorean theorem

In a triangle, the short right-angle side a, the long right-angle side b, and the hypotenuse c. Then there is a formula  

Now we come to prove this Pythagorean theorem:

Take four identical triangles, translate and flip them into the square on the right, then there is an area relationship

This is my country’s great mathematician Zhao Shuang’s method of proof