Question about solving equations – Mathematica Stack Exchange

I want to solve the equation and use the code below.

Solve[2*t^3 + t^2 - θ*t - 2*θ == 0, t]

Then I have three roots. Here, I suppose two roots are an imaginary number and one is a real number. In addition, the three roots are theta function.
Now, I'm trying to solve another problem by assuming that theta = 1 and using the code

Solve[2*t^3 + t^2 - t - 2 == 0, t]

This gives a positive real root 1 and two imaginary roots.
However, if I plug 1 into the actual positive root of the first equation, the root of the first equation is not equal to 1. I use the code below.

F[θ_] : = - (1/6) - (-1 - 6 * θ) /
(6 * (- 1 + 99 * θ +
3 * Sqrt[3]* Sqrt[-8*θ + 359*θ^2 - 8*θ^3]) ^
(1/3)) + (1/6) * (- 1 + 99 * θ + 3 * Sqrt[3]*
sqrt[-8*θ + 359*θ^2 - 8*θ^3]) (1/3)

and

F[1] 

Why are the results in two ways different?