To describe it in simple terms, consider any two quantities where each quantity is greater than zero. Let us say the two quantities have the ratio m:n. Now calculate the sum of the two aforementioned quantities and find the ratio of that sum to any larger quantity of the two, let us call it ratio x:y. If it turns out that ratios m:n and x:y are same, then the two quantities are described as being in a golden ratio.
Algebraically, for quantities b and a where a>b>0, it is expressed as;
((a+b)/a)=def a/b=phi where phi denotes the golden ratio.
Using the above descriptions, if you were to take a perfect square with sides a and place it adjacent to a rectangle that matches its “height” (“height” of the square) but with at least half of the square’s breadth b, then two will form a similar golden rectangle with the longer side of the golden triangle being a+b and the shorter side being a. Therefore, a is to b as a+b is to a. the golden ratio has a decimal approximation of 1.6180339887…