Line 36: Line 36:
 
Visualizations of the golden ratio can be seen below (Weisstein):
 
Visualizations of the golden ratio can be seen below (Weisstein):
  
<center>[[File:Visualization 1.png|frameless]] </center>
+
<center>[[File:Visualization 1.png|framed]] </center>
 
<center>[[File:Visualization 2.png|framed]] </center>
 
<center>[[File:Visualization 2.png|framed]] </center>
  
 
[https://www.mathsisfun.com/numbers/golden-ratio.html MathIsFun] also has an interactive display that can construct a rectangle in the golden ratio given a certain fixed width or length.
 
[https://www.mathsisfun.com/numbers/golden-ratio.html MathIsFun] also has an interactive display that can construct a rectangle in the golden ratio given a certain fixed width or length.

Revision as of 16:36, 2 December 2018

Introduction

The golden ratio is a ratio such that, given two quantities a and b,

$ \frac{a+b}{a} = \frac{a}{b} $

We can solve this equation to find an explicit quantity for the ratio.

$ LHS = \frac{a}{b} + \frac{b}{a} = 1 + \frac{b}{a} $
$ 1 + \frac{b}{a} = \frac{a}{b} $

We set the ratio equal to a certain quantity given by r.

$ r = \frac{a}{b} $

Then we can solve for the ratio numerically.

$ 1 + \frac{1}{r} = r $
$ r + 1 = r^2 $

We can see from the above result that the golden ratio can also be described as a ratio such that in order to get the square of the ratio, you add one to the ratio.

$ r^2 - r - 1 = 0 $

We can then apply the quadratic formula to solve for the roots of the equation.

$ r = \frac{1 \pm \sqrt{1^2 - 4(1)(-1)}}{2} = \frac{1 \pm \sqrt{5}}{2} $

The positive root is then the golden ratio.

$ \frac{1 \pm \sqrt{5}}{2} = \phi $

The golden ratio, $ \phi $, is sometimes also called the golden mean or the golden section. The golden ratio can be frequently observed in man-made objects, though they are generally “imperfectly golden” – that is, the ratio is approximately the golden ratio, but not exactly. Some everyday examples include: credit cards, $ \frac{w}{h}=1.604 $, and laptop screens, $ \frac{w}{h}=1.602 $ (Tannenbaum 392).

Visualizations of the golden ratio can be seen below (Weisstein):

Visualization 1.png
Visualization 2.png

MathIsFun also has an interactive display that can construct a rectangle in the golden ratio given a certain fixed width or length.

Alumni Liaison

Ph.D. 2007, working on developing cool imaging technologies for digital cameras, camera phones, and video surveillance cameras.

Buyue Zhang