## Phi

1·61803 39887 49894 84820 45868 34365 63811 77203 09179 80576 50

28621 35448 62270 52604 62818 90244 97072 07204 18939 11374 100

84754 08807 53868 91752 12663 38622 23536 93179 31800 60766 72635 44333 89086 160

Phi represents the golden ratio, or dividing a line into extreme and mean ratio.
Both Pi and Phi are irrational numbers with infinite numbers after their decimal points.
Phi is the only number whose square is greater than itself by 1.

The Greek Parthenon’s dimensions were modeled on Phi by the sculptor Phidias in 447BC.
The first recorded definition of Phi comes from the Greek mathematician Euclid in the 2nd century BC.
The ratio of sequential elements of the Fibonacci sequence approaches Phi asymptotically.

Text areas in books published between 1550 and 1770 are based on the value of the golden ratio phi.
The ratio of the length of the body of a Stradivarius violin to its neck is Phi
The great pyramid at Giza’s apothem is equal to Phi times its semi base, which makes it a golden pyramid.

German psychologist Adolph Zeising found the golden ratio in many different measurements of natural proportion and hypothesized that Phi is integral to human perception of proportion and beauty. He called it the divine proportion.