Se da la desigualdad:
$$- 2 \sqrt{3} \sin{\left(x \right)} \cos{\left(x \right)} + 2 \sin^{2}{\left(x \right)} > 1 + \sqrt{2}$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$- 2 \sqrt{3} \sin{\left(x \right)} \cos{\left(x \right)} + 2 \sin^{2}{\left(x \right)} = 1 + \sqrt{2}$$
Resolvemos:
$$x_{1} = 2 \operatorname{atan}{\left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{6} \right)}$$
$$x_{2} = - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{3} \right)}$$
$$x_{3} = - 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)}$$
$$x_{4} = - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3} \right)}$$
$$x_{1} = 2 \operatorname{atan}{\left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{6} \right)}$$
$$x_{2} = - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{3} \right)}$$
$$x_{3} = - 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)}$$
$$x_{4} = - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3} \right)}$$
Las raíces dadas
$$x_{3} = - 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)}$$
$$x_{2} = - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{3} \right)}$$
$$x_{4} = - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3} \right)}$$
$$x_{1} = 2 \operatorname{atan}{\left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{6} \right)}$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} < x_{3}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{3} - \frac{1}{10}$$
=
$$- 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} - \frac{1}{10}$$
=
$$- 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} - \frac{1}{10}$$
lo sustituimos en la expresión
$$- 2 \sqrt{3} \sin{\left(x \right)} \cos{\left(x \right)} + 2 \sin^{2}{\left(x \right)} > 1 + \sqrt{2}$$
$$- 2 \sqrt{3} \sin{\left(- 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} - \frac{1}{10} \right)} \cos{\left(- 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} - \frac{1}{10} \right)} + 2 \sin^{2}{\left(- 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} - \frac{1}{10} \right)} > 1 + \sqrt{2}$$
/ / _______________________________________________ \\ / / _______________________________________________ \\ / / _______________________________________________ \\
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| | / / _____________\ _____________|| | | / / _____________\ _____________|| | | / / _____________\ _____________|| ___
2|1 | ___ / | ___ ___ ___ / ___ | ___ ___ / ___ || ___ |1 | ___ / | ___ ___ ___ / ___ | ___ ___ / ___ || |1 | ___ / | ___ ___ ___ / ___ | ___ ___ / ___ || > 1 + \/ 2
2*sin |-- + 2*atan\\/ 3 + \/ 1 + \\/ 3 - \/ 6 + \/ 2 *\/ 3 - 2*\/ 2 / - \/ 6 + \/ 2 *\/ 3 - 2*\/ 2 /| + 2*\/ 3 *cos|-- + 2*atan\\/ 3 + \/ 1 + \\/ 3 - \/ 6 + \/ 2 *\/ 3 - 2*\/ 2 / - \/ 6 + \/ 2 *\/ 3 - 2*\/ 2 /|*sin|-- + 2*atan\\/ 3 + \/ 1 + \\/ 3 - \/ 6 + \/ 2 *\/ 3 - 2*\/ 2 / - \/ 6 + \/ 2 *\/ 3 - 2*\/ 2 /|
\10 / \10 / \10 /
Entonces
$$x < - 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)}$$
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
$$x > - 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} \wedge x < - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{3} \right)}$$
_____ _____
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-------ο-------ο-------ο-------ο-------
x3 x2 x4 x1
Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
$$x > - 2 \operatorname{atan}{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{3} \right)} \wedge x < - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{3} \right)}$$
$$x > - 2 \operatorname{atan}{\left(- \sqrt{6} - \sqrt{\left(- \sqrt{6} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3}\right)^{2} + 1} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{3} \right)} \wedge x < 2 \operatorname{atan}{\left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{1 + \left(- \sqrt{3} + \sqrt{2} \sqrt{3 - 2 \sqrt{2}} + \sqrt{6}\right)^{2}} + \sqrt{6} \right)}$$