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sin^2x-0.5sinx-0.5=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
   2      sin(x)   1    
sin (x) - ------ - - = 0
            2      2    
$$\left(\sin^{2}{\left(x \right)} - \frac{\sin{\left(x \right)}}{2}\right) - \frac{1}{2} = 0$$
Solución detallada
Tenemos la ecuación
$$\left(\sin^{2}{\left(x \right)} - \frac{\sin{\left(x \right)}}{2}\right) - \frac{1}{2} = 0$$
cambiamos
$$\sin^{2}{\left(x \right)} - \frac{\sin{\left(x \right)}}{2} - \frac{1}{2} = 0$$
$$\left(\sin^{2}{\left(x \right)} - \frac{\sin{\left(x \right)}}{2}\right) - \frac{1}{2} = 0$$
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
$$a = 1$$
$$b = - \frac{1}{2}$$
$$c = - \frac{1}{2}$$
, entonces
D = b^2 - 4 * a * c = 

(-1/2)^2 - 4 * (1) * (-1/2) = 9/4

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

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

o
$$w_{1} = 1$$
$$w_{2} = - \frac{1}{2}$$
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:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(1 \right)}$$
$$x_{1} = 2 \pi n + \frac{\pi}{2}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(- \frac{1}{2} \right)}$$
$$x_{2} = 2 \pi n - \frac{\pi}{6}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(1 \right)} + \pi$$
$$x_{3} = 2 \pi n + \frac{\pi}{2}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(- \frac{1}{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \frac{7 \pi}{6}$$
Gráfica
Respuesta rápida [src]
     -pi 
x1 = ----
      6  
$$x_{1} = - \frac{\pi}{6}$$
     pi
x2 = --
     2 
$$x_{2} = \frac{\pi}{2}$$
     7*pi
x3 = ----
      6  
$$x_{3} = \frac{7 \pi}{6}$$
x3 = 7*pi/6
Suma y producto de raíces [src]
suma
  pi   pi   7*pi
- -- + -- + ----
  6    2     6  
$$\left(- \frac{\pi}{6} + \frac{\pi}{2}\right) + \frac{7 \pi}{6}$$
=
3*pi
----
 2  
$$\frac{3 \pi}{2}$$
producto
-pi  pi 7*pi
----*--*----
 6   2   6  
$$\frac{7 \pi}{6} \cdot - \frac{\pi}{6} \frac{\pi}{2}$$
=
     3
-7*pi 
------
  72  
$$- \frac{7 \pi^{3}}{72}$$
-7*pi^3/72
Respuesta numérica [src]
x1 = 629.88932728012
x2 = -75.9218224617533
x3 = -36.1283154198995
x4 = -38.2227106186758
x5 = -34.0339204138894
x6 = 70.6858345098172
x7 = -54.9778719400612
x8 = -0.523598775598299
x9 = 41.3643032722656
x10 = -46.6002910282486
x11 = 14.1371671029003
x12 = 12.0427718387609
x13 = 47.6474885794452
x14 = 24.60914245312
x15 = 91.6297857297023
x16 = -17.2787597988071
x17 = -48.6946859199052
x18 = 100.007366139275
x19 = -90.5825881785057
x20 = 30.8923277602996
x21 = 66.497044500984
x22 = -40.317105721069
x23 = -44.5058959258554
x24 = 16.2315620435473
x25 = 32.986722670018
x26 = 74.8746249105567
x27 = 22.5147473507269
x28 = 83.2522056280779
x29 = -105.243352993987
x30 = 60.2138591938044
x31 = 68.5914396033772
x32 = 58.1194644720255
x33 = 93.7241808320955
x34 = -10.9955744709241
x35 = 56.025068989018
x36 = -57.0722665402146
x37 = 20.4203521503825
x38 = 7.85398173972726
x39 = -65.4498469497874
x40 = -23.5619450081821
x41 = -84.2994028713261
x42 = 64.402649309204
x43 = 53.9306738866248
x44 = 39.2699083672181
x45 = -61.2610569525587
x46 = -82.2050077689329
x47 = -25.6563400043166
x48 = 83.2522055084245
x49 = -92.6769830653709
x50 = 76.9690198127977
x51 = 89.5353908426683
x52 = -78.0162175641465
x53 = 51.8362788989008
x54 = -29.8451300966669
x55 = -4.71238877564271
x56 = -42.4115006190379
x57 = 45.5530936891365
x58 = 5.75958653158129
x59 = 95.8185760576709
x60 = -54.9778716096663
x61 = -80.1106125800495
x62 = -142.942465507123
x63 = 9.94837673636768
x64 = -21.4675497995303
x65 = -2.61799387799149
x66 = 18.3259571459405
x67 = -10.9955748250458
x68 = -98.9601689600088
x69 = -98.9601687457423
x70 = 1.57079653522944
x71 = -88.4881930761125
x72 = 72.7802298081635
x73 = -73.8274272801063
x74 = 49.7418836818384
x75 = 62.3082542961976
x76 = 3.66519142918809
x77 = -59.1666616426078
x78 = -71.733032256967
x79 = -13.0899693899575
x80 = 26.7035384882866
x81 = -19.3731546971371
x82 = -69.6386371545737
x83 = -27.7507351067098
x84 = 97.9129710368819
x85 = 85.3466004225227
x86 = 26.7035373553251
x87 = -63.3554518473942
x88 = -67.5442421664985
x89 = -31.9395253114962
x90 = -86.3937977736525
x90 = -86.3937977736525