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Mystic Math

The golden ratio is the ratio such that the whole portion to the larger portion equals the larger portion to the lesser, or in other words, we have that a/b=b/c when a=b+c.



(a/b) = (b/c) when a = b + c


(a/b) = (b/c)

ac = b^2

a = b + c

c = a - b

a(a - b) = b^2

a^2 - ab = b^2

a^2 - ab - b^2 = 0

(a^2/b^2) - (a/b) - 1 = 0

the last equation is a quadratic in a/b.

(a^2/b^2) - (a/b) = 1

(a^2/b^2) - (a/b) + (1/4) = (5/4)

((a/b) - (1/2))^2 = (5/4)

(a/b) - (1/2) = (sqrt5)/2

a/b = (sqrt5 + 1)/2

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