The
proof:
Looking at diagram 1, it is clear that the area of square A is equal
to a2, the area of
square B is equal to b2,
and the area of square C is equal to c2.
This means that our proof is complete if we can show that the sum of the
areas of square A and square B is equal to the area of square C.
This can be done by printing out (do this!) the diagram from this page
(or the last page) and cutting out squares A and B, further cutting square
A along its dotted lines, and finally placing those pieces along with square
B over the top of square C to verify that the areas are the same.