Sr Examen

Otras calculadoras

cos(2x-pi*1/4)>1/2 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
   /      pi\      
cos|2*x - --| > 1/2
   \      4 /      
$$\cos{\left(2 x - \frac{\pi}{4} \right)} > \frac{1}{2}$$
cos(2*x - pi/4) > 1/2
Solución detallada
Se da la desigualdad:
$$\cos{\left(2 x - \frac{\pi}{4} \right)} > \frac{1}{2}$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$\cos{\left(2 x - \frac{\pi}{4} \right)} = \frac{1}{2}$$
Resolvemos:
Tenemos la ecuación
$$\cos{\left(2 x - \frac{\pi}{4} \right)} = \frac{1}{2}$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$2 x + \frac{\pi}{4} = 2 \pi n + \operatorname{asin}{\left(\frac{1}{2} \right)}$$
$$2 x + \frac{\pi}{4} = 2 \pi n - \operatorname{asin}{\left(\frac{1}{2} \right)} + \pi$$
O
$$2 x + \frac{\pi}{4} = 2 \pi n + \frac{\pi}{6}$$
$$2 x + \frac{\pi}{4} = 2 \pi n + \frac{5 \pi}{6}$$
, donde n es cualquier número entero
Transportemos
$$\frac{\pi}{4}$$
al miembro derecho de la ecuación
con el signo opuesto, en total:
$$2 x = 2 \pi n - \frac{\pi}{12}$$
$$2 x = 2 \pi n + \frac{7 \pi}{12}$$
Dividamos ambos miembros de la ecuación obtenida en
$$2$$
$$x_{1} = \pi n - \frac{\pi}{24}$$
$$x_{2} = \pi n + \frac{7 \pi}{24}$$
$$x_{1} = \pi n - \frac{\pi}{24}$$
$$x_{2} = \pi n + \frac{7 \pi}{24}$$
Las raíces dadas
$$x_{1} = \pi n - \frac{\pi}{24}$$
$$x_{2} = \pi n + \frac{7 \pi}{24}$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} < x_{1}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{1} - \frac{1}{10}$$
=
$$\left(\pi n - \frac{\pi}{24}\right) + - \frac{1}{10}$$
=
$$\pi n - \frac{\pi}{24} - \frac{1}{10}$$
lo sustituimos en la expresión
$$\cos{\left(2 x - \frac{\pi}{4} \right)} > \frac{1}{2}$$
$$\cos{\left(2 \left(\pi n - \frac{\pi}{24} - \frac{1}{10}\right) - \frac{\pi}{4} \right)} > \frac{1}{2}$$
   /1   pi         \      
cos|- + -- - 2*pi*n| > 1/2
   \5   3          /      

Entonces
$$x < \pi n - \frac{\pi}{24}$$
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
$$x > \pi n - \frac{\pi}{24} \wedge x < \pi n + \frac{7 \pi}{24}$$
         _____  
        /     \  
-------ο-------ο-------
       x1      x2
Solución de la desigualdad en el gráfico
Respuesta rápida [src]
  /   /               /                                                        /          ___________________________________________________________________________________________________________________________________________________________________________________________________________\\\     /            /                                                             /          _______________________________________________________________________________________________________________________________________________________________________________________________________\\    \\
  |   |               |        /   /    /      ___             ___    \\\      |         /                                                   /    /         ___                   ___       \\                                                     /    /         ___                   ___       \\ |||     |            |  /         /   /    /      ___             ___    \\\\      |         /                                                   /    /          ___                 ___      \\                                                     /    /          ___                 ___      \\ ||    ||
  |   |               |        |   |    |    \/ 2            \/ 6     |||      |        /                                                    |    |       \/ 2                  \/ 6        ||                                                     |    |       \/ 2                  \/ 6        || |||     |            |  |         |   |    |    \/ 2            \/ 6     ||||      |        /                                                    |    |        \/ 6                \/ 2       ||                                                     |    |        \/ 6                \/ 2       || ||    ||
  |   |               |        |   |atan|------------- + -------------|||      |       /                                                     |atan|------------------- + -------------------||                                                     |atan|------------------- + -------------------|| |||     |            |  |         |   |atan|------------- - -------------||||      |       /                                                     |atan|- ----------------- + -----------------||                                                     |atan|- ----------------- + -----------------|| ||    ||
  |   |               |        |   |    |  ___     ___     ___     ___|||      |      /          _______________________________________     |    |  /    ___     ___\     /    ___     ___\||         _______________________________________     |    |  /    ___     ___\     /    ___     ___\|| |||     |            |  |         |   |    |  ___     ___     ___     ___||||      |      /          _______________________________________     |    |    /  ___     ___\     /  ___     ___\||         _______________________________________     |    |    /  ___     ___\     /  ___     ___\|| ||    ||
  |   |               |        |   |    \\/ 2  - \/ 6    \/ 2  - \/ 6 /||      |     /          /                  2                  2      |    |  |  \/ 6    \/ 2 |     |  \/ 6    \/ 2 |||        /                  2                  2      |    |  |  \/ 6    \/ 2 |     |  \/ 6    \/ 2 ||| |||     |            |  |         |   |    \\/ 2  + \/ 6    \/ 2  + \/ 6 /|||      |     /          /                  2                  2      |    |    |\/ 2    \/ 6 |     |\/ 2    \/ 6 |||        /                  2                  2      |    |    |\/ 2    \/ 6 |     |\/ 2    \/ 6 ||| ||    ||
  |   |               |        |cos|-----------------------------------||      |    /          /  /    ___     ___\    /  ___     ___\       |    |4*|- ----- + -----|   4*|- ----- + -----|||       /  /    ___     ___\    /  ___     ___\       |    |4*|- ----- + -----|   4*|- ----- + -----||| |||     |            |  |         |sin|-----------------------------------|||      |    /          /  /    ___     ___\    /  ___     ___\       |    |  4*|----- + -----|   4*|----- + -----|||       /  /    ___     ___\    /  ___     ___\       |    |  4*|----- + -----|   4*|----- + -----||| ||    ||
  |   |               |        |   \                 2                 /|      |   /          /   |  \/ 6    \/ 2 |    |\/ 2    \/ 6 |      2|    \  \    4       4  /     \    4       4  //|      /   |  \/ 6    \/ 2 |    |\/ 2    \/ 6 |      2|    \  \    4       4  /     \    4       4  //| |||     |            |  |         |   \                 2                 /||      |   /          /   |  \/ 6    \/ 2 |    |\/ 2    \/ 6 |      2|    \    \  4       4  /     \  4       4  //|      /   |  \/ 6    \/ 2 |    |\/ 2    \/ 6 |      2|    \    \  4       4  /     \  4       4  //| ||    ||
Or|And|0 <= x, x < -I*|- I*atan|----------------------------------------| + log|  /          /    |- ----- + -----|  + |----- + -----|  *cos |-----------------------------------------------| +   /    |- ----- + -----|  + |----- + -----|  *sin |-----------------------------------------------| |||, And|x <= pi, -I*|I*|pi + atan|----------------------------------------|| + log|  /          /    |- ----- + -----|  + |----- + -----|  *cos |---------------------------------------------| +   /    |- ----- + -----|  + |----- + -----|  *sin |---------------------------------------------| || < x||
  |   |               |        |   /    /      ___             ___    \\|      \\/         \/     \    4       4  /    \  4       4  /       \                       2                       /   \/     \    4       4  /    \  4       4  /       \                       2                       / /||     |            |  |         |   /    /      ___             ___    \\||      \\/         \/     \    4       4  /    \  4       4  /       \                      2                      /   \/     \    4       4  /    \  4       4  /       \                      2                      / /|    ||
  |   |               |        |   |    |    \/ 2            \/ 6     |||                                                                                                                                                                                                                             ||     |            |  |         |   |    |    \/ 2            \/ 6     ||||                                                                                                                                                                                                                         |    ||
  |   |               |        |   |atan|------------- + -------------|||                                                                                                                                                                                                                             ||     |            |  |         |   |atan|------------- - -------------||||                                                                                                                                                                                                                         |    ||
  |   |               |        |   |    |  ___     ___     ___     ___|||                                                                                                                                                                                                                             ||     |            |  |         |   |    |  ___     ___     ___     ___||||                                                                                                                                                                                                                         |    ||
  |   |               |        |   |    \\/ 2  - \/ 6    \/ 2  - \/ 6 /||                                                                                                                                                                                                                             ||     |            |  |         |   |    \\/ 2  + \/ 6    \/ 2  + \/ 6 /|||                                                                                                                                                                                                                         |    ||
  |   |               |        |sin|-----------------------------------||                                                                                                                                                                                                                             ||     |            |  |         |cos|-----------------------------------|||                                                                                                                                                                                                                         |    ||
  \   \               \        \   \                 2                 //                                                                                                                                                                                                                             //     \            \  \         \   \                 2                 ///                                                                                                                                                                                                                         /    //
$$\left(0 \leq x \wedge x < - i \left(\log{\left(\sqrt{\sqrt{\left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)^{2} + \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)^{2}} \sin^{2}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{6}}{4 \left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)} + \frac{\sqrt{2}}{4 \left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)} \right)}}{2} \right)} + \sqrt{\left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)^{2} + \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)^{2}} \cos^{2}{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{6}}{4 \left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)} + \frac{\sqrt{2}}{4 \left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)} \right)}}{2} \right)}} \right)} - i \operatorname{atan}{\left(\frac{\cos{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{6}}{- \sqrt{6} + \sqrt{2}} + \frac{\sqrt{2}}{- \sqrt{6} + \sqrt{2}} \right)}}{2} \right)}}{\sin{\left(\frac{\operatorname{atan}{\left(\frac{\sqrt{6}}{- \sqrt{6} + \sqrt{2}} + \frac{\sqrt{2}}{- \sqrt{6} + \sqrt{2}} \right)}}{2} \right)}} \right)}\right)\right) \vee \left(x \leq \pi \wedge - i \left(\log{\left(\sqrt{\sqrt{\left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)^{2} + \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)^{2}} \sin^{2}{\left(\frac{\operatorname{atan}{\left(- \frac{\sqrt{6}}{4 \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)} + \frac{\sqrt{2}}{4 \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)} \right)}}{2} \right)} + \sqrt{\left(- \frac{\sqrt{6}}{4} + \frac{\sqrt{2}}{4}\right)^{2} + \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)^{2}} \cos^{2}{\left(\frac{\operatorname{atan}{\left(- \frac{\sqrt{6}}{4 \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)} + \frac{\sqrt{2}}{4 \left(\frac{\sqrt{2}}{4} + \frac{\sqrt{6}}{4}\right)} \right)}}{2} \right)}} \right)} + i \left(\operatorname{atan}{\left(\frac{\sin{\left(\frac{\operatorname{atan}{\left(- \frac{\sqrt{6}}{\sqrt{2} + \sqrt{6}} + \frac{\sqrt{2}}{\sqrt{2} + \sqrt{6}} \right)}}{2} \right)}}{\cos{\left(\frac{\operatorname{atan}{\left(- \frac{\sqrt{6}}{\sqrt{2} + \sqrt{6}} + \frac{\sqrt{2}}{\sqrt{2} + \sqrt{6}} \right)}}{2} \right)}} \right)} + \pi\right)\right) < x\right)$$
((x <= pi)∧(-i*(i*(pi + atan(sin(atan(sqrt(2)/(sqrt(2) + sqrt(6)) - sqrt(6)/(sqrt(2) + sqrt(6)))/2)/cos(atan(sqrt(2)/(sqrt(2) + sqrt(6)) - sqrt(6)/(sqrt(2) + sqrt(6)))/2))) + log(sqrt(sqrt((-sqrt(6)/4 + sqrt(2)/4)^2 + (sqrt(2)/4 + sqrt(6)/4)^2)*cos(atan(-sqrt(6)/(4*(sqrt(2)/4 + sqrt(6)/4)) + sqrt(2)/(4*(sqrt(2)/4 + sqrt(6)/4)))/2)^2 + sqrt((-sqrt(6)/4 + sqrt(2)/4)^2 + (sqrt(2)/4 + sqrt(6)/4)^2)*sin(atan(-sqrt(6)/(4*(sqrt(2)/4 + sqrt(6)/4)) + sqrt(2)/(4*(sqrt(2)/4 + sqrt(6)/4)))/2)^2))) < x))∨((0 <= x)∧(x < -i*(-i*atan(cos(atan(sqrt(2)/(sqrt(2) - sqrt(6)) + sqrt(6)/(sqrt(2) - sqrt(6)))/2)/sin(atan(sqrt(2)/(sqrt(2) - sqrt(6)) + sqrt(6)/(sqrt(2) - sqrt(6)))/2)) + log(sqrt(sqrt((-sqrt(6)/4 + sqrt(2)/4)^2 + (sqrt(2)/4 + sqrt(6)/4)^2)*cos(atan(sqrt(2)/(4*(-sqrt(6)/4 + sqrt(2)/4)) + sqrt(6)/(4*(-sqrt(6)/4 + sqrt(2)/4)))/2)^2 + sqrt((-sqrt(6)/4 + sqrt(2)/4)^2 + (sqrt(2)/4 + sqrt(6)/4)^2)*sin(atan(sqrt(2)/(4*(-sqrt(6)/4 + sqrt(2)/4)) + sqrt(6)/(4*(-sqrt(6)/4 + sqrt(2)/4)))/2)^2)))))