Here is one of the best pages on the internet that covers Phi (and it's reciprocal, phi):
http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/phi.html
It's esay to understand and quite fascinating !!!!
The value of phi is (1 + √5) / 2.
For a more complete explanation, research "golden ratio" or "golden section" on the internet.
Here is one of the best pages on the internet that covers Phi (and it's reciprocal, phi):
http://www.maths.surrey.ac.uk/hosted-sites/R.Knott/Fibonacci/phi.html
It's esay to understand and quite fascinating !!!!