Da Vinci's Pythagorean Proof Method

Da Vinci, a famous painter, studied Pythagorean Theorem, and his method of verifying Pythagorean Theorem can be reflected in the following experiments:

1. Draw two squares with sides A and B on a rectangular cardboard to connect BC and Fe (as shown in figure (1)).

2. Cut along ABCDEFA to get two pieces of cardboard 1 2 with the same size, as shown in Figure (2).

3. Turn the cardboard 2 upside down and combine it with 1 to form a graph as shown in Figure (3).

4. Compare the areas of two polygons ABCDEF and A'B'C'D'E'F in Figure (1) and Figure (3) to verify the Pythagorean theorem.