` 2 cos alpha = x + 1/x `
`2 x cos alpha = x^2 + 1`
`x^2 - 2x cos alpha - 1= 0`
`x = -((-2cos alpha) +- sqrt(4 cos^2 alpha- 4))/2`
`= cos alpha +- i sin alpha`
`= e^(i alpha) or e^(-i alpha)`
`x = e^(i alpha) or e^(-i alpha)`
`y = e^(i beta) or e^(- i beta)`
`z = e^( i gamma) or e^(- i gamma)`
`xyx = e^(i(+- alpha +- beta +- gamma))`
`1/(xyz) = e^(-i(+- alpha +- beta +- gamma))`
`xyz + 1/(xyz) = e^(i phi) + e^(- i phi)= 2 Re ( e^(i phi))`
`= 2 cos phi `
`= 2 cos ( +- alpha +- beta +- gamma)`
option 2 is correct
