I do not see your picture but suspect you are talking about what is often called the "golden ratio".
http://en.wikipedia.org/wiki/Golden_ratio
A rectangular piece of paper has an area of 100 rt2 cm^2. The piece of paper is such that, when it is folded in half along the dashed line, the new rectangle is similar (of the same shape) to the original rectangle. What are the dimensions of the piece of paper?
4 answers
if the length is x and the height is y, we need
y/x = (x/2)/y
x^2 = 2y^2
x = √2 y
since xy = 100√2
y=10
x=10√2
y/x = (x/2)/y
x^2 = 2y^2
x = √2 y
since xy = 100√2
y=10
x=10√2
a(a+b) = 100
but
b = 2a/(1+sqrt5)
a [ a + 2a/(1+sqrt5) ]=100
a^2 [ 1 +2/(1+sqrt5) ] = 100
etc
but
b = 2a/(1+sqrt5)
a [ a + 2a/(1+sqrt5) ]=100
a^2 [ 1 +2/(1+sqrt5) ] = 100
etc
Oh, did no. notice the "in half"