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sin(x)^2>3/5 desigualdades

En la desigualdad la incógnita

Solución

Ha introducido [src]
   2         
sin (x) > 3/5
$$\sin^{2}{\left(x \right)} > \frac{3}{5}$$
sin(x)^2 > 3/5
Solución detallada
Se da la desigualdad:
$$\sin^{2}{\left(x \right)} > \frac{3}{5}$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$\sin^{2}{\left(x \right)} = \frac{3}{5}$$
Resolvemos:
Tenemos la ecuación
$$\sin^{2}{\left(x \right)} = \frac{3}{5}$$
cambiamos
$$\sin^{2}{\left(x \right)} - \frac{3}{5} = 0$$
$$\sin^{2}{\left(x \right)} - \frac{3}{5} = 0$$
Sustituimos
$$w = \sin{\left(x \right)}$$
Es la ecuación de la forma
a*w^2 + b*w + c = 0

La ecuación cuadrática puede ser resuelta
con la ayuda del discriminante.
Las raíces de la ecuación cuadrática:
$$w_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$w_{2} = \frac{- \sqrt{D} - b}{2 a}$$
donde D = b^2 - 4*a*c es el discriminante.
Como
$$a = 1$$
$$b = 0$$
$$c = - \frac{3}{5}$$
, entonces
D = b^2 - 4 * a * c = 

(0)^2 - 4 * (1) * (-3/5) = 12/5

Como D > 0 la ecuación tiene dos raíces.
w1 = (-b + sqrt(D)) / (2*a)

w2 = (-b - sqrt(D)) / (2*a)

o
$$w_{1} = \frac{\sqrt{15}}{5}$$
$$w_{2} = - \frac{\sqrt{15}}{5}$$
hacemos cambio inverso
$$\sin{\left(x \right)} = w$$
Tenemos la ecuación
$$\sin{\left(x \right)} = w$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
O
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
, donde n es cualquier número entero
sustituimos w:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(- \frac{\sqrt{15}}{5} \right)}$$
$$x_{2} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(- \frac{\sqrt{15}}{5} \right)} + \pi$$
$$x_{4} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
$$x_{1} = \pi - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{2} = \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
$$x_{3} = - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{4} = \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{1} = \pi - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{2} = \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
$$x_{3} = - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{4} = \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
Las raíces dadas
$$x_{3} = - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{4} = \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{1} = \pi - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x_{2} = \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
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
$$x_{0} = x_{3} - \frac{1}{10}$$
=
$$- \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} - \frac{1}{10}$$
=
$$- \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} - \frac{1}{10}$$
lo sustituimos en la expresión
$$\sin^{2}{\left(x \right)} > \frac{3}{5}$$
$$\sin^{2}{\left(- \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} - \frac{1}{10} \right)} > \frac{3}{5}$$
    /         /  ____\\      
   2|1        |\/ 15 ||      
sin |-- + asin|------|| > 3/5
    \10       \  5   //      
      

significa que una de las soluciones de nuestra ecuación será con:
$$x < - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
 _____           _____           _____          
      \         /     \         /
-------ο-------ο-------ο-------ο-------
       x3      x4      x1      x2

Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
$$x < - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x > \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} \wedge x < \pi - \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)}$$
$$x > \operatorname{asin}{\left(\frac{\sqrt{15}}{5} \right)} + \pi$$
Solución de la desigualdad en el gráfico
Respuesta rápida [src]
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  \   \       \  \      \   \      2      //       /                                                        /     \  \         \   \      2      ///                                                        /    /     \       \  \         \   \      2      ///                                                        /     \      \   \      2      //                                                        /    //
$$\left(x < - i \left(\log{\left(\sqrt{\sin^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)} + \cos^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)} + i \left(- \operatorname{atan}{\left(\frac{\cos{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}}{\sin{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)} + 2 \pi\right)\right) \wedge - i \left(\log{\left(\sqrt{\sin^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)} + \cos^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)} + i \left(\operatorname{atan}{\left(\frac{\cos{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}}{\sin{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)} + \pi\right)\right) < x\right) \vee \left(x < - i \left(\log{\left(\sqrt{\sin^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)} + \cos^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)} + i \left(\pi - \operatorname{atan}{\left(\frac{\cos{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}}{\sin{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)}\right)\right) \wedge - i \left(\log{\left(\sqrt{\sin^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)} + \cos^{2}{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)} + i \operatorname{atan}{\left(\frac{\cos{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}}{\sin{\left(\frac{\operatorname{atan}{\left(2 \sqrt{6} \right)}}{2} \right)}} \right)}\right) < x\right)$$
((-i*(i*atan(cos(atan(2*sqrt(6))/2)/sin(atan(2*sqrt(6))/2)) + log(sqrt(cos(atan(2*sqrt(6))/2)^2 + sin(atan(2*sqrt(6))/2)^2))) < x)∧(x < -i*(i*(pi - atan(cos(atan(2*sqrt(6))/2)/sin(atan(2*sqrt(6))/2))) + log(sqrt(cos(atan(2*sqrt(6))/2)^2 + sin(atan(2*sqrt(6))/2)^2)))))∨((-i*(i*(pi + atan(cos(atan(2*sqrt(6))/2)/sin(atan(2*sqrt(6))/2))) + log(sqrt(cos(atan(2*sqrt(6))/2)^2 + sin(atan(2*sqrt(6))/2)^2))) < x)∧(x < -i*(i*(-atan(cos(atan(2*sqrt(6))/2)/sin(atan(2*sqrt(6))/2)) + 2*pi) + log(sqrt(cos(atan(2*sqrt(6))/2)^2 + sin(atan(2*sqrt(6))/2)^2)))))