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sin(x)^2=1/2

sin(x)^2=1/2 equation

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Numerical solution:

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The solution

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   2         
sin (x) = 1/2
$$\sin^{2}{\left(x \right)} = \frac{1}{2}$$
Detail solution
Given the equation
$$\sin^{2}{\left(x \right)} = \frac{1}{2}$$
transform
$$- \frac{\cos{\left(2 x \right)}}{2} = 0$$
$$\sin^{2}{\left(x \right)} - \frac{1}{2} = 0$$
Do replacement
$$w = \sin{\left(x \right)}$$
This equation is of the form
a*w^2 + b*w + c = 0

A quadratic equation can be solved
using the discriminant.
The roots of the quadratic equation:
$$w_{1} = \frac{\sqrt{D} - b}{2 a}$$
$$w_{2} = \frac{- \sqrt{D} - b}{2 a}$$
where D = b^2 - 4*a*c - it is the discriminant.
Because
$$a = 1$$
$$b = 0$$
$$c = - \frac{1}{2}$$
, then
D = b^2 - 4 * a * c = 

(0)^2 - 4 * (1) * (-1/2) = 2

Because D > 0, then the equation has two roots.
w1 = (-b + sqrt(D)) / (2*a)

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

or
$$w_{1} = \frac{\sqrt{2}}{2}$$
Simplify
$$w_{2} = - \frac{\sqrt{2}}{2}$$
Simplify
do backward replacement
$$\sin{\left(x \right)} = w$$
Given the equation
$$\sin{\left(x \right)} = w$$
- this is the simplest trigonometric equation
This equation is transformed to
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
Or
$$x = 2 \pi n + \operatorname{asin}{\left(w \right)}$$
$$x = 2 \pi n - \operatorname{asin}{\left(w \right)} + \pi$$
, where n - is a integer
substitute w:
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(w_{1} \right)}$$
$$x_{1} = 2 \pi n + \operatorname{asin}{\left(\frac{\sqrt{2}}{2} \right)}$$
$$x_{1} = 2 \pi n + \frac{\pi}{4}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(w_{2} \right)}$$
$$x_{2} = 2 \pi n + \operatorname{asin}{\left(- \frac{\sqrt{2}}{2} \right)}$$
$$x_{2} = 2 \pi n - \frac{\pi}{4}$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(w_{1} \right)} + \pi$$
$$x_{3} = 2 \pi n - \operatorname{asin}{\left(\frac{\sqrt{2}}{2} \right)} + \pi$$
$$x_{3} = 2 \pi n + \frac{3 \pi}{4}$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(w_{2} \right)} + \pi$$
$$x_{4} = 2 \pi n - \operatorname{asin}{\left(- \frac{\sqrt{2}}{2} \right)} + \pi$$
$$x_{4} = 2 \pi n + \frac{5 \pi}{4}$$
The graph
Rapid solution [src]
     -pi 
x1 = ----
      4  
$$x_{1} = - \frac{\pi}{4}$$
     pi
x2 = --
     4 
$$x_{2} = \frac{\pi}{4}$$
     3*pi
x3 = ----
      4  
$$x_{3} = \frac{3 \pi}{4}$$
     5*pi
x4 = ----
      4  
$$x_{4} = \frac{5 \pi}{4}$$
Sum and product of roots [src]
sum
    pi   pi   3*pi   5*pi
0 - -- + -- + ---- + ----
    4    4     4      4  
$$\left(\left(\left(- \frac{\pi}{4} + 0\right) + \frac{\pi}{4}\right) + \frac{3 \pi}{4}\right) + \frac{5 \pi}{4}$$
=
2*pi
$$2 \pi$$
product
  -pi  pi 3*pi 5*pi
1*----*--*----*----
   4   4   4    4  
$$\frac{5 \pi}{4} \frac{3 \pi}{4} \frac{\pi}{4} \cdot 1 \left(- \frac{\pi}{4}\right)$$
=
      4
-15*pi 
-------
  256  
$$- \frac{15 \pi^{4}}{256}$$
-15*pi^4/256
Numerical answer [src]
x1 = 49.4800842940392
x2 = 162.577419823272
x3 = -35.3429173528852
x4 = 33.7721210260903
x5 = 63.6172512351933
x6 = -62.0464549083984
x7 = -85.6083998103219
x8 = -71.4712328691678
x9 = -90.3207887907066
x10 = -77.7544181763474
x11 = 8.63937979737193
x12 = -19.6349540849362
x13 = 87.1791961371168
x14 = -11.7809724509617
x15 = -41.6261026600648
x16 = -10.2101761241668
x17 = 82.4668071567321
x18 = 44.7676953136546
x19 = 32.2013246992954
x20 = 96.6039740978861
x21 = 60.4756585816035
x22 = -54.1924732744239
x23 = -18.0641577581413
x24 = -13.3517687777566
x25 = 47.9092879672443
x26 = -79.3252145031423
x27 = -24.3473430653209
x28 = -91.8915851175014
x29 = 5.49778714378214
x30 = -46.3384916404494
x31 = 30.6305283725005
x32 = -33.7721210260903
x33 = 2.35619449019234
x34 = 16.4933614313464
x35 = -49.4800842940392
x36 = 66.7588438887831
x37 = -1144.32512407008
x38 = -55.7632696012188
x39 = -3.92699081698724
x40 = 3.92699081698724
x41 = -84.037603483527
x42 = 84.037603483527
x43 = 85.6083998103219
x44 = -69.9004365423729
x45 = 54.1924732744239
x46 = -2.35619449019234
x47 = -57.3340659280137
x48 = -40.0553063332699
x49 = 22.776546738526
x50 = -68.329640215578
x51 = -76.1836218495525
x52 = 38.484510006475
x53 = 41.6261026600648
x54 = 88.7499924639117
x55 = 24.3473430653209
x56 = 27.4889357189107
x57 = 384.059701901352
x58 = 52.621676947629
x59 = -60.4756585816035
x60 = 91.8915851175014
x61 = -98.174770424681
x62 = -32.2013246992954
x63 = 19.6349540849362
x64 = 74.6128255227576
x65 = 69.9004365423729
x66 = -47.9092879672443
x67 = -63.6172512351933
x68 = -5.49778714378214
x69 = -99.7455667514759
x70 = -16.4933614313464
x71 = 99.7455667514759
x72 = 25.9181393921158
x73 = 98.174770424681
x74 = 76.1836218495525
x75 = 62.0464549083984
x76 = 55.7632696012188
x77 = -25.9181393921158
x78 = -27.4889357189107
x79 = -82.4668071567321
x80 = -93.4623814442964
x81 = -38.484510006475
x82 = 18.0641577581413
x83 = 68.329640215578
x84 = 90.3207887907066
x85 = 46.3384916404494
x86 = 10.2101761241668
x87 = 40.0553063332699
x88 = 77.7544181763474
x89 = 11.7809724509617
x89 = 11.7809724509617
The graph
sin(x)^2=1/2 equation