`PT`
`<=> 4sin² x + 4sin x + 1 - (2sin² x - 3sin x + sin x - 3/2) = 0`
`<=> 4sin² x + 4sin x + 1 - 2sin² x + 3sin x - sin x + 3/2 = 0`
`<=> 2sin² x + 6sin x + 5/2 = 0`
`<=> 4sin² x + 12sin x + 5 = 0`
`<=>` \(\left[ \begin{array}{l}sin x = -\dfrac{1}{2}\\sin x = -\dfrac{5}{2} (l)\end{array} \right.\)
`=> sin x = sin (-π/6)`
`<=>` \(\left[ \begin{array}{l}x = -\dfrac{π}{6} + k2π\\x = \dfrac{7π}{6} + k2π\end{array} \right.\) `(k ∈ ZZ)`
