Is there a formula for Phi?

I suspect it's Adobe Flash player as that's what seems to be running the animation.

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Yep...the "formula" is

[ 1 + √5 ] / 2  ≈ 1.618

And the reciprocal of this is "phi"   (i.e., "little Phi").....which =  just the decimal part of Phi = .618   !!!

Here's a website that explains how Phi can be derived from the diagonals of a pentagon.....

http://www.matematicasvisuales.com/english/html/geometry/goldenratio/pentagondiagonal.html

When I tried to look at that site Chris I was told that I needed a plug in.

It did not specify which one  

Does anyone know how I can fix this problem?

Thanks Alan.  I though I already had that but I shall check. :/

I installed the newest version of Adobe Flash player but it still tells me that a 'plug in' is needed