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2sin^2x+cos^2x-3sinx-5=0 la ecuación

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Solución numérica:

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Solución

Ha introducido [src]
     2         2                      
2*sin (x) + cos (x) - 3*sin(x) - 5 = 0
((2sin2(x)+cos2(x))3sin(x))5=0\left(\left(2 \sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) - 3 \sin{\left(x \right)}\right) - 5 = 0
Solución detallada
Tenemos la ecuación
((2sin2(x)+cos2(x))3sin(x))5=0\left(\left(2 \sin^{2}{\left(x \right)} + \cos^{2}{\left(x \right)}\right) - 3 \sin{\left(x \right)}\right) - 5 = 0
cambiamos
sin2(x)3sin(x)4=0\sin^{2}{\left(x \right)} - 3 \sin{\left(x \right)} - 4 = 0
sin2(x)3sin(x)4=0\sin^{2}{\left(x \right)} - 3 \sin{\left(x \right)} - 4 = 0
Sustituimos
w=sin(x)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:
w1=Db2aw_{1} = \frac{\sqrt{D} - b}{2 a}
w2=Db2aw_{2} = \frac{- \sqrt{D} - b}{2 a}
donde D = b^2 - 4*a*c es el discriminante.
Como
a=1a = 1
b=3b = -3
c=4c = -4
, entonces
D = b^2 - 4 * a * c = 

(-3)^2 - 4 * (1) * (-4) = 25

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

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

o
w1=4w_{1} = 4
w2=1w_{2} = -1
hacemos cambio inverso
sin(x)=w\sin{\left(x \right)} = w
Tenemos la ecuación
sin(x)=w\sin{\left(x \right)} = w
es la ecuación trigonométrica más simple
Esta ecuación se reorganiza en
x=2πn+asin(w)x = 2 \pi n + \operatorname{asin}{\left(w \right)}
x=2πnasin(w)+πx = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi
O
x=2πn+asin(w)x = 2 \pi n + \operatorname{asin}{\left(w \right)}
x=2πnasin(w)+πx = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi
, donde n es cualquier número entero
sustituimos w:
x1=2πn+asin(w1)x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}
x1=2πn+asin(4)x_{1} = 2 \pi n + \operatorname{asin}{\left(4 \right)}
x1=2πn+asin(4)x_{1} = 2 \pi n + \operatorname{asin}{\left(4 \right)}
x2=2πn+asin(w2)x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}
x2=2πn+asin(1)x_{2} = 2 \pi n + \operatorname{asin}{\left(-1 \right)}
x2=2πnπ2x_{2} = 2 \pi n - \frac{\pi}{2}
x3=2πnasin(w1)+πx_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi
x3=2πn+πasin(4)x_{3} = 2 \pi n + \pi - \operatorname{asin}{\left(4 \right)}
x3=2πn+πasin(4)x_{3} = 2 \pi n + \pi - \operatorname{asin}{\left(4 \right)}
x4=2πnasin(w2)+πx_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi
x4=2πnasin(1)+πx_{4} = 2 \pi n - \operatorname{asin}{\left(-1 \right)} + \pi
x4=2πn+3π2x_{4} = 2 \pi n + \frac{3 \pi}{2}
Gráfica
0-80-60-40-2020406080-1001005-10
Suma y producto de raíces [src]
suma
           /    /        ____\\         /    /        ____\\       /    /        ____\\         /    /        ____\\
  pi       |    |1   I*\/ 15 ||         |    |1   I*\/ 15 ||       |    |1   I*\/ 15 ||         |    |1   I*\/ 15 ||
- -- + 2*re|atan|- - --------|| + 2*I*im|atan|- - --------|| + 2*re|atan|- + --------|| + 2*I*im|atan|- + --------||
  2        \    \4      4    //         \    \4      4    //       \    \4      4    //         \    \4      4    //
(π2+(2re(atan(1415i4))+2iim(atan(1415i4))))+(2re(atan(14+15i4))+2iim(atan(14+15i4)))\left(- \frac{\pi}{2} + \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)}\right)\right) + \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)}\right)
=
    /    /        ____\\       /    /        ____\\              /    /        ____\\         /    /        ____\\
    |    |1   I*\/ 15 ||       |    |1   I*\/ 15 ||   pi         |    |1   I*\/ 15 ||         |    |1   I*\/ 15 ||
2*re|atan|- - --------|| + 2*re|atan|- + --------|| - -- + 2*I*im|atan|- - --------|| + 2*I*im|atan|- + --------||
    \    \4      4    //       \    \4      4    //   2          \    \4      4    //         \    \4      4    //
π2+2re(atan(1415i4))+2re(atan(14+15i4))+2iim(atan(1415i4))+2iim(atan(14+15i4))- \frac{\pi}{2} + 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)} + 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)}
producto
     /    /    /        ____\\         /    /        ____\\\ /    /    /        ____\\         /    /        ____\\\
-pi  |    |    |1   I*\/ 15 ||         |    |1   I*\/ 15 ||| |    |    |1   I*\/ 15 ||         |    |1   I*\/ 15 |||
----*|2*re|atan|- - --------|| + 2*I*im|atan|- - --------|||*|2*re|atan|- + --------|| + 2*I*im|atan|- + --------|||
 2   \    \    \4      4    //         \    \4      4    /// \    \    \4      4    //         \    \4      4    ///
π2(2re(atan(1415i4))+2iim(atan(1415i4)))(2re(atan(14+15i4))+2iim(atan(14+15i4)))- \frac{\pi}{2} \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)}\right) \left(2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)}\right)
=
      /    /    /        ____\\     /    /        ____\\\ /    /    /        ____\\     /    /        ____\\\
      |    |    |1   I*\/ 15 ||     |    |1   I*\/ 15 ||| |    |    |1   I*\/ 15 ||     |    |1   I*\/ 15 |||
-2*pi*|I*im|atan|- - --------|| + re|atan|- - --------|||*|I*im|atan|- + --------|| + re|atan|- + --------|||
      \    \    \4      4    //     \    \4      4    /// \    \    \4      4    //     \    \4      4    ///
2π(re(atan(1415i4))+iim(atan(1415i4)))(re(atan(14+15i4))+iim(atan(14+15i4)))- 2 \pi \left(\operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)}\right) \left(\operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)} + i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)}\right)
-2*pi*(i*im(atan(1/4 - i*sqrt(15)/4)) + re(atan(1/4 - i*sqrt(15)/4)))*(i*im(atan(1/4 + i*sqrt(15)/4)) + re(atan(1/4 + i*sqrt(15)/4)))
Respuesta rápida [src]
     -pi 
x1 = ----
      2  
x1=π2x_{1} = - \frac{\pi}{2}
         /    /        ____\\         /    /        ____\\
         |    |1   I*\/ 15 ||         |    |1   I*\/ 15 ||
x2 = 2*re|atan|- - --------|| + 2*I*im|atan|- - --------||
         \    \4      4    //         \    \4      4    //
x2=2re(atan(1415i4))+2iim(atan(1415i4))x_{2} = 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} - \frac{\sqrt{15} i}{4} \right)}\right)}
         /    /        ____\\         /    /        ____\\
         |    |1   I*\/ 15 ||         |    |1   I*\/ 15 ||
x3 = 2*re|atan|- + --------|| + 2*I*im|atan|- + --------||
         \    \4      4    //         \    \4      4    //
x3=2re(atan(14+15i4))+2iim(atan(14+15i4))x_{3} = 2 \operatorname{re}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)} + 2 i \operatorname{im}{\left(\operatorname{atan}{\left(\frac{1}{4} + \frac{\sqrt{15} i}{4} \right)}\right)}
x3 = 2*re(atan(1/4 + sqrt(15)*i/4)) + 2*i*im(atan(1/4 + sqrt(15)*i/4))
Respuesta numérica [src]
x1 = -45.5530933379328
x2 = -83.2522055607843
x3 = 98.9601682813222
x4 = -64.402649173144
x5 = -58.1194639983404
x6 = -20.4203520160774
x7 = -89.5353904664517
x8 = -51.8362786894957
x9 = -83.2522049833183
x10 = -76.9690196523847
x11 = -76.9690203364266
x12 = 67.5442422976148
x13 = -14.1371668379482
x14 = 92.676983594607
x15 = 4.71238875280883
x16 = 23.5619451408423
x17 = 23.5619445854305
x18 = -76.9690194223839
x19 = 80.110613139437
x20 = -32.9867229016282
x21 = 29.8451303220427
x22 = -39.2699084040555
x23 = -14.137166267618
x24 = 73.8274272534934
x25 = 92.6769830669358
x26 = 36.1283157093032
x27 = -64.4026497009475
x28 = 98.9601689505548
x29 = 42.4115009127929
x30 = -89.5353907488532
x31 = -32.9867225012491
x32 = 48.6946864510303
x33 = -45.5530935900185
x34 = 61.2610570733106
x35 = -32.9867229219624
x36 = -158.650429510901
x37 = 61.2610563902501
x38 = 54.9778711266118
x39 = -95.8185758680815
x40 = -20.4203525581159
x41 = 2122.14583792168
x42 = 17.2787599191456
x43 = -32.9867231822668
x44 = -70.6858343897312
x45 = -26.7035379113368
x46 = -39.2699078379722
x47 = -227.765467380722
x48 = -14.1371669906886
x49 = 48.6946859098066
x50 = -58.119464108743
x51 = -51.8362794146821
x52 = 10.9955739720808
x53 = 42.411500728142
x54 = -7.85398149740641
x55 = -1.57079621145266
x56 = -70.6858350616861
x57 = 17.2787592393122
x58 = 54.9778718002295
x59 = 4.71238930682327
x60 = -83.2522056059716
x61 = 10.9955746496251
x62 = 73.8274274816964
x63 = 67.5442417296428
x64 = -95.8185764895439
x65 = -114.668132439338
x66 = -26.7035372352027
x67 = -7.85398233977009
x68 = 86.3937978874973
x69 = -1.57079643102431
x70 = 29.8451301301352
x71 = 86.3937980345907
x71 = 86.3937980345907