Question

This diagram shows a golden rectangle (the large rectangle) whose side lengths are in the approximate ratio of (1 +√5)/2. The rectangle is divided into a square and a smaller rectangle. The side lengths of the smaller rectangle are proportional to the side lengths of the larger rectangle, so the two rectangles are similar. Therefore, the ratio of the side lengths of the smaller rectangle is the golden ratio.

Which of the following is the proportion of the side lengths of the smaller rectangle to the side lengths of the larger rectangle?