Phi

• Phi is an irrational number expressed as • some more symbols used for Phi are Φ, φ, or ϕ. • Phi is also known as the golden mean, golden ratio or golden number. golden ratio • two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities.

golden shapes are based on the golden ratio EXAMPLES: golden rectangle, golden triangle, golden rhombus and the golden spiral