Se da la desigualdad:
$$\left|{\sin{\left(x \right)}}\right| \geq \frac{\sqrt{2}}{2}$$
Para resolver esta desigualdad primero hay que resolver la ecuación correspondiente:
$$\left|{\sin{\left(x \right)}}\right| = \frac{\sqrt{2}}{2}$$
Resolvemos:
Tenemos la ecuación
$$\left|{\sin{\left(x \right)}}\right| = \frac{\sqrt{2}}{2}$$
cambiamos
$$\left|{\sin{\left(x \right)}}\right| - 1 - \frac{\sqrt{2}}{2} = 0$$
$$\left|{\sin{\left(x \right)}}\right| - 1 - \frac{\sqrt{2}}{2} = 0$$
Sustituimos
$$w = \left|{\sin{\left(x \right)}}\right|$$
Abrimos los paréntesis en el miembro izquierdo de la ecuación
-1 + w - sqrt2/2 = 0
Transportamos los términos libres (sin w)
del miembro izquierdo al derecho, obtenemos:
$$w - \frac{\sqrt{2}}{2} = 1$$
Dividamos ambos miembros de la ecuación en (w - sqrt(2)/2)/w
w = 1 / ((w - sqrt(2)/2)/w)
Obtenemos la respuesta: w = 1 + sqrt(2)/2
hacemos cambio inverso
$$\left|{\sin{\left(x \right)}}\right| = w$$
sustituimos w:
$$x_{1} = -41.6261026600648$$
$$x_{2} = 18.0641577581413$$
$$x_{3} = 25.9181393921158$$
$$x_{4} = 41.6261026600648$$
$$x_{5} = 40.0553063332699$$
$$x_{6} = 63.6172512351933$$
$$x_{7} = -47.9092879672443$$
$$x_{8} = 88.7499924639117$$
$$x_{9} = -22.776546738526$$
$$x_{10} = 96.6039740978861$$
$$x_{11} = 82.4668071567321$$
$$x_{12} = -13.3517687777566$$
$$x_{13} = -62.0464549083984$$
$$x_{14} = 44.7676953136546$$
$$x_{15} = -200.276531666349$$
$$x_{16} = 0.785398163397448$$
$$x_{17} = -24.3473430653209$$
$$x_{18} = -16.4933614313464$$
$$x_{19} = 19.6349540849362$$
$$x_{20} = -3.92699081698724$$
$$x_{21} = 52.621676947629$$
$$x_{22} = -84.037603483527$$
$$x_{23} = -49.4800842940392$$
$$x_{24} = -63.6172512351933$$
$$x_{25} = 55.7632696012188$$
$$x_{26} = 91.8915851175014$$
$$x_{27} = -87.1791961371168$$
$$x_{28} = 93.4623814442964$$
$$x_{29} = 60.4756585816035$$
$$x_{30} = -10.2101761241668$$
$$x_{31} = 71.4712328691678$$
$$x_{32} = 32.2013246992954$$
$$x_{33} = -85.6083998103219$$
$$x_{34} = 33.7721210260903$$
$$x_{35} = -57.3340659280137$$
$$x_{36} = -32.2013246992954$$
$$x_{37} = 30.6305283725005$$
$$x_{38} = -82.4668071567321$$
$$x_{39} = 3.92699081698724$$
$$x_{40} = 2.35619449019234$$
$$x_{41} = 16.4933614313464$$
$$x_{42} = 76.1836218495525$$
$$x_{43} = -2.35619449019234$$
$$x_{44} = -21.2057504117311$$
$$x_{45} = -90.3207887907066$$
$$x_{46} = -46.3384916404494$$
$$x_{47} = -98.174770424681$$
$$x_{48} = 46.3384916404494$$
$$x_{49} = 5.49778714378214$$
$$x_{50} = 47.9092879672443$$
$$x_{51} = -43.1968989868597$$
$$x_{52} = 99.7455667514759$$
$$x_{53} = -91.8915851175014$$
$$x_{54} = -33.7721210260903$$
$$x_{55} = -19.6349540849362$$
$$x_{56} = -60.4756585816035$$
$$x_{57} = 27.4889357189107$$
$$x_{58} = -71.4712328691678$$
$$x_{59} = 84.037603483527$$
$$x_{60} = -76.1836218495525$$
$$x_{61} = -38.484510006475$$
$$x_{62} = 22.776546738526$$
$$x_{63} = 68.329640215578$$
$$x_{64} = 66.7588438887831$$
$$x_{65} = -241.117236163017$$
$$x_{66} = -11.7809724509617$$
$$x_{67} = -27.4889357189107$$
$$x_{68} = 62.0464549083984$$
$$x_{69} = -25.9181393921158$$
$$x_{70} = -40.0553063332699$$
$$x_{71} = -65.1880475619882$$
$$x_{72} = -5.49778714378214$$
$$x_{73} = 245.829625143401$$
$$x_{74} = 54.1924732744239$$
$$x_{75} = -35.3429173528852$$
$$x_{76} = 90.3207887907066$$
$$x_{77} = -55.7632696012188$$
$$x_{78} = 11.7809724509617$$
$$x_{79} = 8.63937979737193$$
$$x_{80} = 74.6128255227576$$
$$x_{81} = -54.1924732744239$$
$$x_{82} = -99.7455667514759$$
$$x_{83} = -18.0641577581413$$
$$x_{84} = 38.484510006475$$
$$x_{85} = -77.7544181763474$$
$$x_{86} = -79.3252145031423$$
$$x_{87} = 10.2101761241668$$
$$x_{88} = 85.6083998103219$$
$$x_{89} = 98.174770424681$$
$$x_{90} = -68.329640215578$$
$$x_{91} = 118.595122673015$$
$$x_{92} = -69.9004365423729$$
$$x_{93} = 49.4800842940392$$
$$x_{94} = 69.9004365423729$$
$$x_{95} = 24.3473430653209$$
$$x_{96} = -93.4623814442964$$
$$x_{97} = 77.7544181763474$$
$$x_{1} = -41.6261026600648$$
$$x_{2} = 18.0641577581413$$
$$x_{3} = 25.9181393921158$$
$$x_{4} = 41.6261026600648$$
$$x_{5} = 40.0553063332699$$
$$x_{6} = 63.6172512351933$$
$$x_{7} = -47.9092879672443$$
$$x_{8} = 88.7499924639117$$
$$x_{9} = -22.776546738526$$
$$x_{10} = 96.6039740978861$$
$$x_{11} = 82.4668071567321$$
$$x_{12} = -13.3517687777566$$
$$x_{13} = -62.0464549083984$$
$$x_{14} = 44.7676953136546$$
$$x_{15} = -200.276531666349$$
$$x_{16} = 0.785398163397448$$
$$x_{17} = -24.3473430653209$$
$$x_{18} = -16.4933614313464$$
$$x_{19} = 19.6349540849362$$
$$x_{20} = -3.92699081698724$$
$$x_{21} = 52.621676947629$$
$$x_{22} = -84.037603483527$$
$$x_{23} = -49.4800842940392$$
$$x_{24} = -63.6172512351933$$
$$x_{25} = 55.7632696012188$$
$$x_{26} = 91.8915851175014$$
$$x_{27} = -87.1791961371168$$
$$x_{28} = 93.4623814442964$$
$$x_{29} = 60.4756585816035$$
$$x_{30} = -10.2101761241668$$
$$x_{31} = 71.4712328691678$$
$$x_{32} = 32.2013246992954$$
$$x_{33} = -85.6083998103219$$
$$x_{34} = 33.7721210260903$$
$$x_{35} = -57.3340659280137$$
$$x_{36} = -32.2013246992954$$
$$x_{37} = 30.6305283725005$$
$$x_{38} = -82.4668071567321$$
$$x_{39} = 3.92699081698724$$
$$x_{40} = 2.35619449019234$$
$$x_{41} = 16.4933614313464$$
$$x_{42} = 76.1836218495525$$
$$x_{43} = -2.35619449019234$$
$$x_{44} = -21.2057504117311$$
$$x_{45} = -90.3207887907066$$
$$x_{46} = -46.3384916404494$$
$$x_{47} = -98.174770424681$$
$$x_{48} = 46.3384916404494$$
$$x_{49} = 5.49778714378214$$
$$x_{50} = 47.9092879672443$$
$$x_{51} = -43.1968989868597$$
$$x_{52} = 99.7455667514759$$
$$x_{53} = -91.8915851175014$$
$$x_{54} = -33.7721210260903$$
$$x_{55} = -19.6349540849362$$
$$x_{56} = -60.4756585816035$$
$$x_{57} = 27.4889357189107$$
$$x_{58} = -71.4712328691678$$
$$x_{59} = 84.037603483527$$
$$x_{60} = -76.1836218495525$$
$$x_{61} = -38.484510006475$$
$$x_{62} = 22.776546738526$$
$$x_{63} = 68.329640215578$$
$$x_{64} = 66.7588438887831$$
$$x_{65} = -241.117236163017$$
$$x_{66} = -11.7809724509617$$
$$x_{67} = -27.4889357189107$$
$$x_{68} = 62.0464549083984$$
$$x_{69} = -25.9181393921158$$
$$x_{70} = -40.0553063332699$$
$$x_{71} = -65.1880475619882$$
$$x_{72} = -5.49778714378214$$
$$x_{73} = 245.829625143401$$
$$x_{74} = 54.1924732744239$$
$$x_{75} = -35.3429173528852$$
$$x_{76} = 90.3207887907066$$
$$x_{77} = -55.7632696012188$$
$$x_{78} = 11.7809724509617$$
$$x_{79} = 8.63937979737193$$
$$x_{80} = 74.6128255227576$$
$$x_{81} = -54.1924732744239$$
$$x_{82} = -99.7455667514759$$
$$x_{83} = -18.0641577581413$$
$$x_{84} = 38.484510006475$$
$$x_{85} = -77.7544181763474$$
$$x_{86} = -79.3252145031423$$
$$x_{87} = 10.2101761241668$$
$$x_{88} = 85.6083998103219$$
$$x_{89} = 98.174770424681$$
$$x_{90} = -68.329640215578$$
$$x_{91} = 118.595122673015$$
$$x_{92} = -69.9004365423729$$
$$x_{93} = 49.4800842940392$$
$$x_{94} = 69.9004365423729$$
$$x_{95} = 24.3473430653209$$
$$x_{96} = -93.4623814442964$$
$$x_{97} = 77.7544181763474$$
Las raíces dadas
$$x_{65} = -241.117236163017$$
$$x_{15} = -200.276531666349$$
$$x_{82} = -99.7455667514759$$
$$x_{47} = -98.174770424681$$
$$x_{96} = -93.4623814442964$$
$$x_{53} = -91.8915851175014$$
$$x_{45} = -90.3207887907066$$
$$x_{27} = -87.1791961371168$$
$$x_{33} = -85.6083998103219$$
$$x_{22} = -84.037603483527$$
$$x_{38} = -82.4668071567321$$
$$x_{86} = -79.3252145031423$$
$$x_{85} = -77.7544181763474$$
$$x_{60} = -76.1836218495525$$
$$x_{58} = -71.4712328691678$$
$$x_{92} = -69.9004365423729$$
$$x_{90} = -68.329640215578$$
$$x_{71} = -65.1880475619882$$
$$x_{24} = -63.6172512351933$$
$$x_{13} = -62.0464549083984$$
$$x_{56} = -60.4756585816035$$
$$x_{35} = -57.3340659280137$$
$$x_{77} = -55.7632696012188$$
$$x_{81} = -54.1924732744239$$
$$x_{23} = -49.4800842940392$$
$$x_{7} = -47.9092879672443$$
$$x_{46} = -46.3384916404494$$
$$x_{51} = -43.1968989868597$$
$$x_{1} = -41.6261026600648$$
$$x_{70} = -40.0553063332699$$
$$x_{61} = -38.484510006475$$
$$x_{75} = -35.3429173528852$$
$$x_{54} = -33.7721210260903$$
$$x_{36} = -32.2013246992954$$
$$x_{67} = -27.4889357189107$$
$$x_{69} = -25.9181393921158$$
$$x_{17} = -24.3473430653209$$
$$x_{9} = -22.776546738526$$
$$x_{44} = -21.2057504117311$$
$$x_{55} = -19.6349540849362$$
$$x_{83} = -18.0641577581413$$
$$x_{18} = -16.4933614313464$$
$$x_{12} = -13.3517687777566$$
$$x_{66} = -11.7809724509617$$
$$x_{30} = -10.2101761241668$$
$$x_{72} = -5.49778714378214$$
$$x_{20} = -3.92699081698724$$
$$x_{43} = -2.35619449019234$$
$$x_{16} = 0.785398163397448$$
$$x_{40} = 2.35619449019234$$
$$x_{39} = 3.92699081698724$$
$$x_{49} = 5.49778714378214$$
$$x_{79} = 8.63937979737193$$
$$x_{87} = 10.2101761241668$$
$$x_{78} = 11.7809724509617$$
$$x_{41} = 16.4933614313464$$
$$x_{2} = 18.0641577581413$$
$$x_{19} = 19.6349540849362$$
$$x_{62} = 22.776546738526$$
$$x_{95} = 24.3473430653209$$
$$x_{3} = 25.9181393921158$$
$$x_{57} = 27.4889357189107$$
$$x_{37} = 30.6305283725005$$
$$x_{32} = 32.2013246992954$$
$$x_{34} = 33.7721210260903$$
$$x_{84} = 38.484510006475$$
$$x_{5} = 40.0553063332699$$
$$x_{4} = 41.6261026600648$$
$$x_{14} = 44.7676953136546$$
$$x_{48} = 46.3384916404494$$
$$x_{50} = 47.9092879672443$$
$$x_{93} = 49.4800842940392$$
$$x_{21} = 52.621676947629$$
$$x_{74} = 54.1924732744239$$
$$x_{25} = 55.7632696012188$$
$$x_{29} = 60.4756585816035$$
$$x_{68} = 62.0464549083984$$
$$x_{6} = 63.6172512351933$$
$$x_{64} = 66.7588438887831$$
$$x_{63} = 68.329640215578$$
$$x_{94} = 69.9004365423729$$
$$x_{31} = 71.4712328691678$$
$$x_{80} = 74.6128255227576$$
$$x_{42} = 76.1836218495525$$
$$x_{97} = 77.7544181763474$$
$$x_{11} = 82.4668071567321$$
$$x_{59} = 84.037603483527$$
$$x_{88} = 85.6083998103219$$
$$x_{8} = 88.7499924639117$$
$$x_{76} = 90.3207887907066$$
$$x_{26} = 91.8915851175014$$
$$x_{28} = 93.4623814442964$$
$$x_{10} = 96.6039740978861$$
$$x_{89} = 98.174770424681$$
$$x_{52} = 99.7455667514759$$
$$x_{91} = 118.595122673015$$
$$x_{73} = 245.829625143401$$
son puntos de cambio del signo de desigualdad en las soluciones.
Primero definámonos con el signo hasta el punto extremo izquierdo:
$$x_{0} \leq x_{65}$$
Consideremos, por ejemplo, el punto
$$x_{0} = x_{65} - \frac{1}{10}$$
=
$$-241.117236163017 + - \frac{1}{10}$$
=
$$-241.217236163017$$
lo sustituimos en la expresión
$$\left|{\sin{\left(x \right)}}\right| \geq \frac{\sqrt{2}}{2}$$
$$\left|{\sin{\left(-241.217236163017 \right)}}\right| \geq \frac{\sqrt{2}}{2}$$
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\/ 2
0.632981306676965 >= -----
2
pero
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0.632981306676965 < -----
2
Entonces
$$x \leq -241.117236163017$$
no se cumple
significa que una de las soluciones de nuestra ecuación será con:
$$x \geq -241.117236163017 \wedge x \leq -200.276531666349$$
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x65 x15 x82 x47 x96 x53 x45 x27 x33 x22 x38 x86 x85 x60 x58 x92 x90 x71 x24 x13 x56 x35 x77 x81 x23 x7 x46 x51 x1 x70 x61 x75 x54 x36 x67 x69 x17 x9 x44 x55 x83 x18 x12 x66 x30 x72 x20 x43 x16 x40 x39 x49 x79 x87 x78 x41 x2 x19 x62 x95 x3 x57 x37 x32 x34 x84 x5 x4 x14 x48 x50 x93 x21 x74 x25 x29 x68 x6 x64 x63 x94 x31 x80 x42 x97 x11 x59 x88 x8 x76 x26 x28 x10 x89 x52 x91 x73
Recibiremos otras soluciones de la desigualdad pasando al polo siguiente etc.
etc.
Respuesta:
$$x \geq -241.117236163017 \wedge x \leq -200.276531666349$$
$$x \geq -99.7455667514759 \wedge x \leq -98.174770424681$$
$$x \geq -93.4623814442964 \wedge x \leq -91.8915851175014$$
$$x \geq -90.3207887907066 \wedge x \leq -87.1791961371168$$
$$x \geq -85.6083998103219 \wedge x \leq -84.037603483527$$
$$x \geq -82.4668071567321 \wedge x \leq -79.3252145031423$$
$$x \geq -77.7544181763474 \wedge x \leq -76.1836218495525$$
$$x \geq -71.4712328691678 \wedge x \leq -69.9004365423729$$
$$x \geq -68.329640215578 \wedge x \leq -65.1880475619882$$
$$x \geq -63.6172512351933 \wedge x \leq -62.0464549083984$$
$$x \geq -60.4756585816035 \wedge x \leq -57.3340659280137$$
$$x \geq -55.7632696012188 \wedge x \leq -54.1924732744239$$
$$x \geq -49.4800842940392 \wedge x \leq -47.9092879672443$$
$$x \geq -46.3384916404494 \wedge x \leq -43.1968989868597$$
$$x \geq -41.6261026600648 \wedge x \leq -40.0553063332699$$
$$x \geq -38.484510006475 \wedge x \leq -35.3429173528852$$
$$x \geq -33.7721210260903 \wedge x \leq -32.2013246992954$$
$$x \geq -27.4889357189107 \wedge x \leq -25.9181393921158$$
$$x \geq -24.3473430653209 \wedge x \leq -22.776546738526$$
$$x \geq -21.2057504117311 \wedge x \leq -19.6349540849362$$
$$x \geq -18.0641577581413 \wedge x \leq -16.4933614313464$$
$$x \geq -13.3517687777566 \wedge x \leq -11.7809724509617$$
$$x \geq -10.2101761241668 \wedge x \leq -5.49778714378214$$
$$x \geq -3.92699081698724 \wedge x \leq -2.35619449019234$$
$$x \geq 0.785398163397448 \wedge x \leq 2.35619449019234$$
$$x \geq 3.92699081698724 \wedge x \leq 5.49778714378214$$
$$x \geq 8.63937979737193 \wedge x \leq 10.2101761241668$$
$$x \geq 11.7809724509617 \wedge x \leq 16.4933614313464$$
$$x \geq 18.0641577581413 \wedge x \leq 19.6349540849362$$
$$x \geq 22.776546738526 \wedge x \leq 24.3473430653209$$
$$x \geq 25.9181393921158 \wedge x \leq 27.4889357189107$$
$$x \geq 30.6305283725005 \wedge x \leq 32.2013246992954$$
$$x \geq 33.7721210260903 \wedge x \leq 38.484510006475$$
$$x \geq 40.0553063332699 \wedge x \leq 41.6261026600648$$
$$x \geq 44.7676953136546 \wedge x \leq 46.3384916404494$$
$$x \geq 47.9092879672443 \wedge x \leq 49.4800842940392$$
$$x \geq 52.621676947629 \wedge x \leq 54.1924732744239$$
$$x \geq 55.7632696012188 \wedge x \leq 60.4756585816035$$
$$x \geq 62.0464549083984 \wedge x \leq 63.6172512351933$$
$$x \geq 66.7588438887831 \wedge x \leq 68.329640215578$$
$$x \geq 69.9004365423729 \wedge x \leq 71.4712328691678$$
$$x \geq 74.6128255227576 \wedge x \leq 76.1836218495525$$
$$x \geq 77.7544181763474 \wedge x \leq 82.4668071567321$$
$$x \geq 84.037603483527 \wedge x \leq 85.6083998103219$$
$$x \geq 88.7499924639117 \wedge x \leq 90.3207887907066$$
$$x \geq 91.8915851175014 \wedge x \leq 93.4623814442964$$
$$x \geq 96.6039740978861 \wedge x \leq 98.174770424681$$
$$x \geq 99.7455667514759 \wedge x \leq 118.595122673015$$
$$x \geq 245.829625143401$$