How can the golden ratio be expressed as a geometric mean?
Given a length of segment divided into 2 parts, a and b.
The golden ration is the ratio of:
`(a+b)/a = a/b =phi`
``phi is the ratio of the segment when divided in this special way.
The equation has as its unique positive solution the algebraic irrational number:
`phi = (1+sqrt(5))/2 = 1.61803397887...`