`1) sin 2x - sqrt{3} = 0`
`<=> sin 2x = sqrt{3}`
Vì `-1 ≤ sin 2x ≤ 1 => sin 2x ne sqrt{3}`
`=>` Phương trình vô nghiệm
`2) cos^2 2x - 3cos 2x + 2 = 0`
`<=>` \(\left[ \begin{array}{l}cos 2x = 2 (l)\\cos 2x = 1\end{array} \right.\)
`<=> 2x = k2π`
`<=> x = kπ` `(k in ZZ)`
`3) (sin 2x)/2 - 1= 0`
`<=> sin 2x = 2`
Vì `sin 2x in [-1; 1] => sin 2x ne 2`
`=>` Phương trình vô nghiệm
`4) 2x - π/2 - 1 = 0`
`<=> 2x = π/2 + 1`
`<=> x = π/4 + 1/2`
`=> ????`
`5) (sin x + 1)(cos x - 1) = 0`
`<=>` \(\left[ \begin{array}{l}sin x = -1\\cos x = 1\end{array} \right.\)
`<=>` \(\left[ \begin{array}{l}x = -\dfrac{π}{2} + k2π\\x = k2π\end{array} \right.\) `(k in ZZ)`
