1.61803398874989484820458683436563811772030917980576286213544862270526046281...

1/2 (1 + sqrt(5))

1/2 + sqrt(5)/2

[1; 1^_]

ϕ = 2 sin(54 °)

ϕ = -2 sin(666 °)

ϕ = 2 cos(π/5)