if the length of a rectangle divided by its width is equal to the golden ratio, then the rectangle is a "golden rectangle". if a square is cut off from one end of a golden rectangle, then the other end is a new golden rectangle. in the picture, the big rectangle (blue and pink together) is a golden rectangle because formula_10. the blue part (b) is a square, and the pink part by itself (a) is another golden rectangle because formula_11. the big rectangle and the pink rectangle have the same form, but the pink rectangle is smaller and is turned.