Beauty of phi!

Geometry Level 3

We can express

cos ( π 10 ) = sin ( 2 π 5 ) = a ϕ + b c ( d ϕ + c ) \begin{aligned} \cos \left(\dfrac{\pi}{10} \right) = \sin \left(\dfrac{2\pi}{5}\right) = \dfrac{\sqrt { a\phi + b}}{c\,(d\phi + c)} \end{aligned}

And further express it as

q p c ( ϕ ( ϕ m ψ m + ϕ n ψ n ) + ϕ m 1 ψ m 1 + ϕ n 1 ψ n 1 ϕ ( ϕ t ψ t ) + ϕ t 1 ψ t 1 ) \begin{aligned}\small{\dfrac{\sqrt[p]{q}}{c}\left(\dfrac{\sqrt{ \phi\,(\phi^{m} -\psi^{m} +\phi^{n}-\psi^{n} )+\phi^{m-1} -\psi^{m-1} +\phi^{n-1} -\psi^{n-1}}}{\phi\,(\phi^{t} -\psi^{t} )+\phi^{t-1}-\psi^{t-1} }\right) }\end{aligned} If S S be the smallest possible sum of unknown positive integers excluding the sum of t 1 , m 1 , n 1 t-1,m-1,n-1 where b b , c c , q q , n 1 n-1 and t 1 t-1 are prime integers. Which of the following is the possible value of S S ?


Notations: ϕ = 1 + 5 2 \phi = \dfrac{1+\sqrt 5}{2} denotes the golden ratio and ψ = 1 ϕ \psi = 1-\phi .

This is an original problem

169 146 111 123 100 159

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