Golden Ratio - phi

Two quantities are in thegolden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities. Expressed algebraically, for quantities a and b w itha>b>0,

where the Greek letter phi(ϕorφ) represents the golden ratio. It is an irrational number with a value of:

The Geometric Relationship -

The golden ratio is also called the golden mean or golden section. Other names include extreme and mean ratio, medial section, divine proportion, divine section, golden proportion, golden cut, and golden number.