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cos(2x-(pi/4))x≤-(√3/2) inequation

A inequation with variable

The solution

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                      ___ 
   /      pi\      -\/ 3  
cos|2*x - --|*x <= -------
   \      4 /         2   
$$x \cos{\left(2 x - \frac{\pi}{4} \right)} \leq - \frac{\sqrt{3}}{2}$$
x*cos(2*x - pi/4) <= -sqrt(3)/2
Detail solution
Given the inequality:
$$x \cos{\left(2 x - \frac{\pi}{4} \right)} \leq - \frac{\sqrt{3}}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$x \cos{\left(2 x - \frac{\pi}{4} \right)} = - \frac{\sqrt{3}}{2}$$
Solve:
$$x_{1} = 35.7477306320813$$
$$x_{2} = 90.7087141383207$$
$$x_{3} = 92.2889761903236$$
$$x_{4} = 2.57756789869373$$
$$x_{5} = 4.41833218870582$$
$$x_{6} = -41.2228986266421$$
$$x_{7} = -94.6359030607806$$
$$x_{8} = 65.574143045524$$
$$x_{9} = 98.5718624260433$$
$$x_{10} = -88.3523923305876$$
$$x_{11} = -91.4941532834635$$
$$x_{12} = 87.5669502052005$$
$$x_{13} = -69.501507035948$$
$$x_{14} = -17.6959380645662$$
$$x_{15} = -53.7917240434184$$
$$x_{16} = 46.7219223213739$$
$$x_{17} = -80.5086903111165$$
$$x_{18} = -55.3783900020515$$
$$x_{19} = -25.5084617903844$$
$$x_{20} = -14.5596242389401$$
$$x_{21} = -96.2157755104838$$
$$x_{22} = -61.6607785557254$$
$$x_{23} = -99.3572258649787$$
$$x_{24} = -2.16887082755251$$
$$x_{25} = -97.7776427399657$$
$$x_{26} = -77.367316054284$$
$$x_{27} = -66.3596193779403$$
$$x_{28} = 1.48855960517723$$
$$x_{29} = -23.9727106489827$$
$$x_{30} = 64.0167145801539$$
$$x_{31} = -60.0757514718742$$
$$x_{32} = -16.0737101108477$$
$$x_{33} = 5.81575314037901$$
$$x_{34} = -31.7950050422583$$
$$x_{35} = 10.6436031352424$$
$$x_{36} = 68.7160376509593$$
$$x_{37} = 54.5931043261049$$
$$x_{38} = 62.4322180425498$$
$$x_{39} = 12.137966959545$$
$$x_{40} = 18.4333574770289$$
$$x_{41} = -45.9552156096449$$
$$x_{42} = 48.3109505632436$$
$$x_{43} = -82.0688317633173$$
$$x_{44} = -83.6500809710862$$
$$x_{45} = 21.578377129864$$
$$x_{46} = 78.1415757577305$$
$$x_{47} = 43.5796612954408$$
$$x_{48} = -19.2197177647678$$
$$x_{49} = -67.9433144530403$$
$$x_{50} = -11.4262062008546$$
$$x_{51} = 86.0061336494404$$
$$x_{52} = 34.1521398153172$$
$$x_{53} = -39.6735225187304$$
$$x_{54} = 93.850466602772$$
$$x_{55} = 40.4372963456374$$
$$x_{56} = -104.061095462942$$
$$x_{57} = 76.5819752896018$$
$$x_{58} = -8.29895266969519$$
$$x_{59} = -58.5195628953145$$
$$x_{60} = -38.0804389435651$$
$$x_{61} = 49.8640990821956$$
$$x_{62} = 13.7759211770063$$
$$x_{63} = 32.6073049652536$$
$$x_{64} = 79.7233451333755$$
$$x_{65} = -75.7852089599415$$
$$x_{66} = 100.133941444321$$
$$x_{67} = 27.8660932450522$$
$$x_{68} = 56.1482564243358$$
$$x_{69} = -33.3923908048991$$
$$x_{70} = 84.4251735228072$$
$$x_{71} = 7.51899978446191$$
$$x_{72} = -6.61018866689758$$
$$x_{73} = 24.7225236560155$$
$$x_{74} = -47.5074737578972$$
$$x_{75} = 57.7342653899289$$
$$x_{76} = -3.40573797678636$$
$$x_{77} = 70.2992953395131$$
$$x_{78} = -30.2521447011736$$
$$x_{79} = 71.8579058472682$$
$$x_{80} = 26.3272887370679$$
$$x_{81} = -89.9329046251528$$
$$x_{82} = 20.0492573318314$$
$$x_{83} = 42.029105157638$$
$$x_{84} = -22.3644811896294$$
$$x_{85} = -74.2259602830878$$
$$x_{86} = -9.77311232132626$$
$$x_{87} = -52.2372675901086$$
$$x_{88} = -44.3652354315924$$
$$x_{1} = 35.7477306320813$$
$$x_{2} = 90.7087141383207$$
$$x_{3} = 92.2889761903236$$
$$x_{4} = 2.57756789869373$$
$$x_{5} = 4.41833218870582$$
$$x_{6} = -41.2228986266421$$
$$x_{7} = -94.6359030607806$$
$$x_{8} = 65.574143045524$$
$$x_{9} = 98.5718624260433$$
$$x_{10} = -88.3523923305876$$
$$x_{11} = -91.4941532834635$$
$$x_{12} = 87.5669502052005$$
$$x_{13} = -69.501507035948$$
$$x_{14} = -17.6959380645662$$
$$x_{15} = -53.7917240434184$$
$$x_{16} = 46.7219223213739$$
$$x_{17} = -80.5086903111165$$
$$x_{18} = -55.3783900020515$$
$$x_{19} = -25.5084617903844$$
$$x_{20} = -14.5596242389401$$
$$x_{21} = -96.2157755104838$$
$$x_{22} = -61.6607785557254$$
$$x_{23} = -99.3572258649787$$
$$x_{24} = -2.16887082755251$$
$$x_{25} = -97.7776427399657$$
$$x_{26} = -77.367316054284$$
$$x_{27} = -66.3596193779403$$
$$x_{28} = 1.48855960517723$$
$$x_{29} = -23.9727106489827$$
$$x_{30} = 64.0167145801539$$
$$x_{31} = -60.0757514718742$$
$$x_{32} = -16.0737101108477$$
$$x_{33} = 5.81575314037901$$
$$x_{34} = -31.7950050422583$$
$$x_{35} = 10.6436031352424$$
$$x_{36} = 68.7160376509593$$
$$x_{37} = 54.5931043261049$$
$$x_{38} = 62.4322180425498$$
$$x_{39} = 12.137966959545$$
$$x_{40} = 18.4333574770289$$
$$x_{41} = -45.9552156096449$$
$$x_{42} = 48.3109505632436$$
$$x_{43} = -82.0688317633173$$
$$x_{44} = -83.6500809710862$$
$$x_{45} = 21.578377129864$$
$$x_{46} = 78.1415757577305$$
$$x_{47} = 43.5796612954408$$
$$x_{48} = -19.2197177647678$$
$$x_{49} = -67.9433144530403$$
$$x_{50} = -11.4262062008546$$
$$x_{51} = 86.0061336494404$$
$$x_{52} = 34.1521398153172$$
$$x_{53} = -39.6735225187304$$
$$x_{54} = 93.850466602772$$
$$x_{55} = 40.4372963456374$$
$$x_{56} = -104.061095462942$$
$$x_{57} = 76.5819752896018$$
$$x_{58} = -8.29895266969519$$
$$x_{59} = -58.5195628953145$$
$$x_{60} = -38.0804389435651$$
$$x_{61} = 49.8640990821956$$
$$x_{62} = 13.7759211770063$$
$$x_{63} = 32.6073049652536$$
$$x_{64} = 79.7233451333755$$
$$x_{65} = -75.7852089599415$$
$$x_{66} = 100.133941444321$$
$$x_{67} = 27.8660932450522$$
$$x_{68} = 56.1482564243358$$
$$x_{69} = -33.3923908048991$$
$$x_{70} = 84.4251735228072$$
$$x_{71} = 7.51899978446191$$
$$x_{72} = -6.61018866689758$$
$$x_{73} = 24.7225236560155$$
$$x_{74} = -47.5074737578972$$
$$x_{75} = 57.7342653899289$$
$$x_{76} = -3.40573797678636$$
$$x_{77} = 70.2992953395131$$
$$x_{78} = -30.2521447011736$$
$$x_{79} = 71.8579058472682$$
$$x_{80} = 26.3272887370679$$
$$x_{81} = -89.9329046251528$$
$$x_{82} = 20.0492573318314$$
$$x_{83} = 42.029105157638$$
$$x_{84} = -22.3644811896294$$
$$x_{85} = -74.2259602830878$$
$$x_{86} = -9.77311232132626$$
$$x_{87} = -52.2372675901086$$
$$x_{88} = -44.3652354315924$$
This roots
$$x_{56} = -104.061095462942$$
$$x_{23} = -99.3572258649787$$
$$x_{25} = -97.7776427399657$$
$$x_{21} = -96.2157755104838$$
$$x_{7} = -94.6359030607806$$
$$x_{11} = -91.4941532834635$$
$$x_{81} = -89.9329046251528$$
$$x_{10} = -88.3523923305876$$
$$x_{44} = -83.6500809710862$$
$$x_{43} = -82.0688317633173$$
$$x_{17} = -80.5086903111165$$
$$x_{26} = -77.367316054284$$
$$x_{65} = -75.7852089599415$$
$$x_{85} = -74.2259602830878$$
$$x_{13} = -69.501507035948$$
$$x_{49} = -67.9433144530403$$
$$x_{27} = -66.3596193779403$$
$$x_{22} = -61.6607785557254$$
$$x_{31} = -60.0757514718742$$
$$x_{59} = -58.5195628953145$$
$$x_{18} = -55.3783900020515$$
$$x_{15} = -53.7917240434184$$
$$x_{87} = -52.2372675901086$$
$$x_{74} = -47.5074737578972$$
$$x_{41} = -45.9552156096449$$
$$x_{88} = -44.3652354315924$$
$$x_{6} = -41.2228986266421$$
$$x_{53} = -39.6735225187304$$
$$x_{60} = -38.0804389435651$$
$$x_{69} = -33.3923908048991$$
$$x_{34} = -31.7950050422583$$
$$x_{78} = -30.2521447011736$$
$$x_{19} = -25.5084617903844$$
$$x_{29} = -23.9727106489827$$
$$x_{84} = -22.3644811896294$$
$$x_{48} = -19.2197177647678$$
$$x_{14} = -17.6959380645662$$
$$x_{32} = -16.0737101108477$$
$$x_{20} = -14.5596242389401$$
$$x_{50} = -11.4262062008546$$
$$x_{86} = -9.77311232132626$$
$$x_{58} = -8.29895266969519$$
$$x_{72} = -6.61018866689758$$
$$x_{76} = -3.40573797678636$$
$$x_{24} = -2.16887082755251$$
$$x_{28} = 1.48855960517723$$
$$x_{4} = 2.57756789869373$$
$$x_{5} = 4.41833218870582$$
$$x_{33} = 5.81575314037901$$
$$x_{71} = 7.51899978446191$$
$$x_{35} = 10.6436031352424$$
$$x_{39} = 12.137966959545$$
$$x_{62} = 13.7759211770063$$
$$x_{40} = 18.4333574770289$$
$$x_{82} = 20.0492573318314$$
$$x_{45} = 21.578377129864$$
$$x_{73} = 24.7225236560155$$
$$x_{80} = 26.3272887370679$$
$$x_{67} = 27.8660932450522$$
$$x_{63} = 32.6073049652536$$
$$x_{52} = 34.1521398153172$$
$$x_{1} = 35.7477306320813$$
$$x_{55} = 40.4372963456374$$
$$x_{83} = 42.029105157638$$
$$x_{47} = 43.5796612954408$$
$$x_{16} = 46.7219223213739$$
$$x_{42} = 48.3109505632436$$
$$x_{61} = 49.8640990821956$$
$$x_{37} = 54.5931043261049$$
$$x_{68} = 56.1482564243358$$
$$x_{75} = 57.7342653899289$$
$$x_{38} = 62.4322180425498$$
$$x_{30} = 64.0167145801539$$
$$x_{8} = 65.574143045524$$
$$x_{36} = 68.7160376509593$$
$$x_{77} = 70.2992953395131$$
$$x_{79} = 71.8579058472682$$
$$x_{57} = 76.5819752896018$$
$$x_{46} = 78.1415757577305$$
$$x_{64} = 79.7233451333755$$
$$x_{70} = 84.4251735228072$$
$$x_{51} = 86.0061336494404$$
$$x_{12} = 87.5669502052005$$
$$x_{2} = 90.7087141383207$$
$$x_{3} = 92.2889761903236$$
$$x_{54} = 93.850466602772$$
$$x_{9} = 98.5718624260433$$
$$x_{66} = 100.133941444321$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} \leq x_{56}$$
For example, let's take the point
$$x_{0} = x_{56} - \frac{1}{10}$$
=
$$-104.061095462942 + - \frac{1}{10}$$
=
$$-104.161095462942$$
substitute to the expression
$$x \cos{\left(2 x - \frac{\pi}{4} \right)} \leq - \frac{\sqrt{3}}{2}$$
$$\left(-104.161095462942\right) \cos{\left(\left(-104.161095462942\right) 2 - \frac{\pi}{4} \right)} \leq - \frac{\sqrt{3}}{2}$$
                                                   ___ 
                     /                   pi\    -\/ 3  
-104.161095462942*cos|208.322190925885 + --| <= -------
                     \                   4 /       2   
                                                

but
                                                   ___ 
                     /                   pi\    -\/ 3  
-104.161095462942*cos|208.322190925885 + --| >= -------
                     \                   4 /       2   
                                                

Then
$$x \leq -104.061095462942$$
no execute
one of the solutions of our inequality is:
$$x \geq -104.061095462942 \wedge x \leq -99.3572258649787$$
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       x56      x23      x25      x21      x7      x11      x81      x10      x44      x43      x17      x26      x65      x85      x13      x49      x27      x22      x31      x59      x18      x15      x87      x74      x41      x88      x6      x53      x60      x69      x34      x78      x19      x29      x84      x48      x14      x32      x20      x50      x86      x58      x72      x76      x24      x28      x4      x5      x33      x71      x35      x39      x62      x40      x82      x45      x73      x80      x67      x63      x52      x1      x55      x83      x47      x16      x42      x61      x37      x68      x75      x38      x30      x8      x36      x77      x79      x57      x46      x64      x70      x51      x12      x2      x3      x54      x9      x66

Other solutions will get with the changeover to the next point
etc.
The answer:
$$x \geq -104.061095462942 \wedge x \leq -99.3572258649787$$
$$x \geq -97.7776427399657 \wedge x \leq -96.2157755104838$$
$$x \geq -94.6359030607806 \wedge x \leq -91.4941532834635$$
$$x \geq -89.9329046251528 \wedge x \leq -88.3523923305876$$
$$x \geq -83.6500809710862 \wedge x \leq -82.0688317633173$$
$$x \geq -80.5086903111165 \wedge x \leq -77.367316054284$$
$$x \geq -75.7852089599415 \wedge x \leq -74.2259602830878$$
$$x \geq -69.501507035948 \wedge x \leq -67.9433144530403$$
$$x \geq -66.3596193779403 \wedge x \leq -61.6607785557254$$
$$x \geq -60.0757514718742 \wedge x \leq -58.5195628953145$$
$$x \geq -55.3783900020515 \wedge x \leq -53.7917240434184$$
$$x \geq -52.2372675901086 \wedge x \leq -47.5074737578972$$
$$x \geq -45.9552156096449 \wedge x \leq -44.3652354315924$$
$$x \geq -41.2228986266421 \wedge x \leq -39.6735225187304$$
$$x \geq -38.0804389435651 \wedge x \leq -33.3923908048991$$
$$x \geq -31.7950050422583 \wedge x \leq -30.2521447011736$$
$$x \geq -25.5084617903844 \wedge x \leq -23.9727106489827$$
$$x \geq -22.3644811896294 \wedge x \leq -19.2197177647678$$
$$x \geq -17.6959380645662 \wedge x \leq -16.0737101108477$$
$$x \geq -14.5596242389401 \wedge x \leq -11.4262062008546$$
$$x \geq -9.77311232132626 \wedge x \leq -8.29895266969519$$
$$x \geq -6.61018866689758 \wedge x \leq -3.40573797678636$$
$$x \geq -2.16887082755251 \wedge x \leq 1.48855960517723$$
$$x \geq 2.57756789869373 \wedge x \leq 4.41833218870582$$
$$x \geq 5.81575314037901 \wedge x \leq 7.51899978446191$$
$$x \geq 10.6436031352424 \wedge x \leq 12.137966959545$$
$$x \geq 13.7759211770063 \wedge x \leq 18.4333574770289$$
$$x \geq 20.0492573318314 \wedge x \leq 21.578377129864$$
$$x \geq 24.7225236560155 \wedge x \leq 26.3272887370679$$
$$x \geq 27.8660932450522 \wedge x \leq 32.6073049652536$$
$$x \geq 34.1521398153172 \wedge x \leq 35.7477306320813$$
$$x \geq 40.4372963456374 \wedge x \leq 42.029105157638$$
$$x \geq 43.5796612954408 \wedge x \leq 46.7219223213739$$
$$x \geq 48.3109505632436 \wedge x \leq 49.8640990821956$$
$$x \geq 54.5931043261049 \wedge x \leq 56.1482564243358$$
$$x \geq 57.7342653899289 \wedge x \leq 62.4322180425498$$
$$x \geq 64.0167145801539 \wedge x \leq 65.574143045524$$
$$x \geq 68.7160376509593 \wedge x \leq 70.2992953395131$$
$$x \geq 71.8579058472682 \wedge x \leq 76.5819752896018$$
$$x \geq 78.1415757577305 \wedge x \leq 79.7233451333755$$
$$x \geq 84.4251735228072 \wedge x \leq 86.0061336494404$$
$$x \geq 87.5669502052005 \wedge x \leq 90.7087141383207$$
$$x \geq 92.2889761903236 \wedge x \leq 93.850466602772$$
$$x \geq 98.5718624260433 \wedge x \leq 100.133941444321$$
Solving inequality on a graph