Golden Ratios and Rectangles
A rectangle is "Golden" if the ratio of the longer side to the shorter side is
.
This ratio is called the Golden Ratio.
If you divide a Golden Rectangle into a square and a smaller rectangle, then the smaller rectangle is another Golden Rectangle.
By chopping off successive squares and drawing a quarter circle with a radius equal to the side of the square you are cutting, you will obtain the Golden Spiral. The center of the spiral is obtained by intersecting a diagonal for the largest rectangle with a diagonal for the second-largest rectangle.