Your golden rectangle: long side 100.00, short side 61.80.
The long side (100.0000) divided by the short side (61.8034) equals 1.618034, which is exactly phi (1.618034).
If you cut a square of side b from this rectangle, the leftover piece is itself a golden rectangle, a self-similar property that repeats infinitely.
The golden spiral that fits inside this rectangle touches each successive quarter-circle arc, producing the curve seen in nautilus shells and many natural growth patterns.
Next stepUse the perimeter result to estimate framing material or the area result to estimate canvas or tile coverage.