Name this solution of x^2-x-1=0, an irrational number that approximately equals 1.618.
This number gives the ratio of the side lengths of Penrose tile kites and darts. The Fibonacci [fih-boe-NAH-chee] sequence can be expressed using powers of this number and its reciprocal, and the limiting ratio of successive terms of the Fibonacci sequence equals this number. Removing a square sharing a side with a rectangle whose side lengths are in this ratio leaves another rectangle whose side lengths are in this ratio. Name this solution of x^2-x-1=0, an irrational number that approximately equals 1.618.
This number gives the ratio of the side lengths of Penrose tile kites and darts.
golden ratio (or golden mean or golden section or golden cut or mean of Phidias, accept divine in place of golden, prompt on "phi")