`D = RR \\ {π/6 + k2π; (5π)/6 + k2π | k in ZZ}`
`PT`
`=> sin 2x - cos 2x + 7sin x + 3cos x + 3 = 2sin x - 1`
`<=> sin 2x + 3cos x - cos 2x + 5sin x + 4 = 0`
`<=> 2sin x.cos x + 3cos x - (2sin^2 x - 5sin x - 3) = 0`
`<=> cos x(2sin x + 3) + (2sin x + 3)(sin x + 1) = 0`
`<=> (sin x + cos x + 1)(2sin x + 3) = 0`
`<=>` \(\left[ \begin{array}{l}x + \dfrac{π}{4} = -\dfrac{π}{4} + k2π\\x + \dfrac{π}{4} = \dfrac{5π}{4} + k2π\\sin x = -\dfrac{3}{2} (l)\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = -\dfrac{π}{2} + k2π\\x = π + k2π\end{array} \right.\) `(k in ZZ)`
