Relationship between cosine, imaginary number, logarithm, and the golden ratio
From specialfunctionswiki
Theorem
The following formula holds: $$2\cos(i \log(1+\varphi))=3,$$ where $\cos$ denotes the cosine function, $i$ denotes the imaginary number, $\log$ denotes the logarithm, and $\varphi$ denotes the golden ratio.