Sliding Down the Diagonal

1) Suppose point F moves along the diagonal of a square. What is the relationship between the areas of the two shaded rectangles as F moves? Explain you thinking.[br][br]2) What is the relationship between the areas of the two shaded rectangles when F moves along a diagonal o f a non-square rectangle? Explain your thinking. What is different from the situation of the square, and what is unchanged?[br][br]