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cos^2z-sin^2z=-2 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
   2         2        
cos (z) - sin (z) = -2
$$- \sin^{2}{\left(z \right)} + \cos^{2}{\left(z \right)} = -2$$
Solución detallada
Tenemos la ecuación
$$- \sin^{2}{\left(z \right)} + \cos^{2}{\left(z \right)} = -2$$
cambiamos
$$\cos{\left(2 z \right)} + 2 = 0$$
$$3 - 2 \sin^{2}{\left(z \right)} = 0$$
Sustituimos
$$w = \sin{\left(z \right)}$$
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
$$a = -2$$
$$b = 0$$
$$c = 3$$
, entonces
D = b^2 - 4 * a * c = 

(0)^2 - 4 * (-2) * (3) = 24

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

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

o
$$w_{1} = - \frac{\sqrt{6}}{2}$$
$$w_{2} = \frac{\sqrt{6}}{2}$$
hacemos cambio inverso
$$\sin{\left(z \right)} = w$$
Tenemos la ecuación
$$\sin{\left(z \right)} = w$$
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
$$z = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$z = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
O
$$z = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$z = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
, donde n es cualquier número entero
sustituimos w:
$$z_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$z_{1} = 2 \pi n + \operatorname{asin}{\left(- \frac{\sqrt{6}}{2} \right)}$$
$$z_{1} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{6}}{2} \right)}$$
$$z_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$z_{2} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{6}}{2} \right)}$$
$$z_{2} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{6}}{2} \right)}$$
$$z_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$z_{3} = 2 \pi n + \pi - \operatorname{asin}{\left(- \frac{\sqrt{6}}{2} \right)}$$
$$z_{3} = 2 \pi n + \pi + \operatorname{asin}{\left(\frac{\sqrt{6}}{2} \right)}$$
$$z_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$z_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(\frac{\sqrt{6}}{2} \right)}$$
$$z_{4} = 2 \pi n + \pi - \operatorname{asin}{\left(\frac{\sqrt{6}}{2} \right)}$$
Gráfica
Suma y producto de raíces [src]
suma
      /    /        /    ___\ \\         /    /        /    ___\ \\       /    /        /    ___\ \\         /    /        /    ___\ \\         /    /       /    ___\\\         /    /       /    ___\\\       /    /       /    ___\\\         /    /       /    ___\\\
      |    | -I*atan\2*\/ 2 / ||         |    | -I*atan\2*\/ 2 / ||       |    | -I*atan\2*\/ 2 / ||         |    | -I*atan\2*\/ 2 / ||         |    | I*atan\2*\/ 2 /||         |    | I*atan\2*\/ 2 /||       |    | I*atan\2*\/ 2 /||         |    | I*atan\2*\/ 2 /||
      |    | -----------------||         |    | -----------------||       |    | -----------------||         |    | -----------------||         |    | ---------------||         |    | ---------------||       |    | ---------------||         |    | ---------------||
      |    |         2        ||         |    |         2        ||       |    |         2        ||         |    |         2        ||         |    |        2       ||         |    |        2       ||       |    |        2       ||         |    |        2       ||
- 2*re\atan\e                 // - 2*I*im\atan\e                 // + 2*re\atan\e                 // + 2*I*im\atan\e                 // + - 2*re\atan\e               // - 2*I*im\atan\e               // + 2*re\atan\e               // + 2*I*im\atan\e               //
$$\left(\left(\left(2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right) + \left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right)\right) + \left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right)\right) + \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right)$$
=
0
$$0$$
producto
/      /    /        /    ___\ \\         /    /        /    ___\ \\\ /    /    /        /    ___\ \\         /    /        /    ___\ \\\ /      /    /       /    ___\\\         /    /       /    ___\\\\ /    /    /       /    ___\\\         /    /       /    ___\\\\
|      |    | -I*atan\2*\/ 2 / ||         |    | -I*atan\2*\/ 2 / ||| |    |    | -I*atan\2*\/ 2 / ||         |    | -I*atan\2*\/ 2 / ||| |      |    | I*atan\2*\/ 2 /||         |    | I*atan\2*\/ 2 /||| |    |    | I*atan\2*\/ 2 /||         |    | I*atan\2*\/ 2 /|||
|      |    | -----------------||         |    | -----------------||| |    |    | -----------------||         |    | -----------------||| |      |    | ---------------||         |    | ---------------||| |    |    | ---------------||         |    | ---------------|||
|      |    |         2        ||         |    |         2        ||| |    |    |         2        ||         |    |         2        ||| |      |    |        2       ||         |    |        2       ||| |    |    |        2       ||         |    |        2       |||
\- 2*re\atan\e                 // - 2*I*im\atan\e                 ///*\2*re\atan\e                 // + 2*I*im\atan\e                 ///*\- 2*re\atan\e               // - 2*I*im\atan\e               ///*\2*re\atan\e               // + 2*I*im\atan\e               ///
$$\left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right) \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right) \left(- 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right) \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right)$$
=
                                                              2                                                                2
   /    /    /       /    ___\\\     /    /       /    ___\\\\  /    /    /        /    ___\ \\     /    /        /    ___\ \\\ 
   |    |    | I*atan\2*\/ 2 /||     |    | I*atan\2*\/ 2 /|||  |    |    | -I*atan\2*\/ 2 / ||     |    | -I*atan\2*\/ 2 / ||| 
   |    |    | ---------------||     |    | ---------------|||  |    |    | -----------------||     |    | -----------------||| 
   |    |    |        2       ||     |    |        2       |||  |    |    |         2        ||     |    |         2        ||| 
16*\I*im\atan\e               // + re\atan\e               /// *\I*im\atan\e                 // + re\atan\e                 /// 
$$16 \left(\operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right)^{2} \left(\operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}\right)^{2}$$
16*(i*im(atan(exp(i*atan(2*sqrt(2))/2))) + re(atan(exp(i*atan(2*sqrt(2))/2))))^2*(i*im(atan(exp(-i*atan(2*sqrt(2))/2))) + re(atan(exp(-i*atan(2*sqrt(2))/2))))^2
Respuesta rápida [src]
           /    /        /    ___\ \\         /    /        /    ___\ \\
           |    | -I*atan\2*\/ 2 / ||         |    | -I*atan\2*\/ 2 / ||
           |    | -----------------||         |    | -----------------||
           |    |         2        ||         |    |         2        ||
z1 = - 2*re\atan\e                 // - 2*I*im\atan\e                 //
$$z_{1} = - 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}$$
         /    /        /    ___\ \\         /    /        /    ___\ \\
         |    | -I*atan\2*\/ 2 / ||         |    | -I*atan\2*\/ 2 / ||
         |    | -----------------||         |    | -----------------||
         |    |         2        ||         |    |         2        ||
z2 = 2*re\atan\e                 // + 2*I*im\atan\e                 //
$$z_{2} = 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{- \frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}$$
           /    /       /    ___\\\         /    /       /    ___\\\
           |    | I*atan\2*\/ 2 /||         |    | I*atan\2*\/ 2 /||
           |    | ---------------||         |    | ---------------||
           |    |        2       ||         |    |        2       ||
z3 = - 2*re\atan\e               // - 2*I*im\atan\e               //
$$z_{3} = - 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} - 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}$$
         /    /       /    ___\\\         /    /       /    ___\\\
         |    | I*atan\2*\/ 2 /||         |    | I*atan\2*\/ 2 /||
         |    | ---------------||         |    | ---------------||
         |    |        2       ||         |    |        2       ||
z4 = 2*re\atan\e               // + 2*I*im\atan\e               //
$$z_{4} = 2 \operatorname{re}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(e^{\frac{i \operatorname{atan}{\left(2 \sqrt{2} \right)}}{2}} \right)}\right)}$$
z4 = 2*re(atan(exp(i*atan(2*sqrt(2))/2))) + 2*i*im(atan(exp(i*atan(2*sqrt(2))/2)))
Respuesta numérica [src]
z1 = -1.5707963267949 + 0.658478948462408*i
z2 = 1.5707963267949 - 0.658478948462408*i
z3 = -1.5707963267949 - 0.658478948462408*i
z4 = 1.5707963267949 + 0.658478948462408*i
z4 = 1.5707963267949 + 0.658478948462408*i