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cost<1/3 inequation

A inequation with variable

The solution

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cos(t) < 1/3
$$\cos{\left(t \right)} < \frac{1}{3}$$
cos(t) < 1/3
Detail solution
Given the inequality:
$$\cos{\left(t \right)} < \frac{1}{3}$$
To solve this inequality, we must first solve the corresponding equation:
$$\cos{\left(t \right)} = \frac{1}{3}$$
Solve:
Given the equation
$$\cos{\left(t \right)} = \frac{1}{3}$$
transform
$$\cos{\left(t \right)} - \frac{1}{3} = 0$$
$$\cos{\left(t \right)} - \frac{1}{3} = 0$$
Do replacement
$$w = \cos{\left(t \right)}$$
Move free summands (without w)
from left part to right part, we given:
$$w = \frac{1}{3}$$
We get the answer: w = 1/3
do backward replacement
$$\cos{\left(t \right)} = w$$
substitute w:
$$x_{1} = -86.7336348831734$$
$$x_{2} = -49.0345230400959$$
$$x_{3} = -61.6008936544551$$
$$x_{4} = 42.7513377329163$$
$$x_{5} = -99.3000054975326$$
$$x_{6} = -30.1849671185572$$
$$x_{7} = 5.05222588983881$$
$$x_{8} = -51.4964418747775$$
$$x_{9} = -101.761924332214$$
$$x_{10} = 20.0805153388795$$
$$x_{11} = -38.9300712604183$$
$$x_{12} = -55.3177083472755$$
$$x_{13} = 36.4681524257367$$
$$x_{14} = 86.7336348831734$$
$$x_{15} = -80.4504495759938$$
$$x_{16} = 11.3354111970184$$
$$x_{17} = 32.6468859532387$$
$$x_{18} = -36.4681524257367$$
$$x_{19} = -57.7796271819571$$
$$x_{20} = 93.016820190353$$
$$x_{21} = 23.9017818113776$$
$$x_{22} = -26.3637006460591$$
$$x_{23} = 76.6291831034958$$
$$x_{24} = -325.494676555998$$
$$x_{25} = -13.7973300316999$$
$$x_{26} = -32.6468859532387$$
$$x_{27} = 95.4787390250346$$
$$x_{28} = 30.1849671185572$$
$$x_{29} = -93.016820190353$$
$$x_{30} = -17.618596504198$$
$$x_{31} = 67.8840789616347$$
$$x_{32} = 17.618596504198$$
$$x_{33} = 82.9123684106754$$
$$x_{34} = 45.2132565675979$$
$$x_{35} = 51.4964418747775$$
$$x_{36} = 7.51414472452036$$
$$x_{37} = 61.6008936544551$$
$$x_{38} = -67.8840789616347$$
$$x_{39} = 64.0628124891366$$
$$x_{40} = 38.9300712604183$$
$$x_{41} = -64.0628124891366$$
$$x_{42} = 70.3459977963162$$
$$x_{43} = 13.7973300316999$$
$$x_{44} = 89.195553717855$$
$$x_{45} = -76.6291831034958$$
$$x_{46} = -1.23095941734077$$
$$x_{47} = -7.51414472452036$$
$$x_{48} = -82.9123684106754$$
$$x_{49} = 99.3000054975326$$
$$x_{50} = 74.1672642688143$$
$$x_{51} = 1.23095941734077$$
$$x_{52} = -11.3354111970184$$
$$x_{53} = 80.4504495759938$$
$$x_{54} = -23.9017818113776$$
$$x_{55} = -5.05222588983881$$
$$x_{56} = -20.0805153388795$$
$$x_{57} = -45.2132565675979$$
$$x_{58} = 26.3637006460591$$
$$x_{59} = 57.7796271819571$$
$$x_{60} = -95.4787390250346$$
$$x_{61} = 55.3177083472755$$
$$x_{62} = 49.0345230400959$$
$$x_{63} = -42.7513377329163$$
$$x_{64} = -89.195553717855$$
$$x_{65} = -70.3459977963162$$
$$x_{66} = -74.1672642688143$$
$$x_{1} = -86.7336348831734$$
$$x_{2} = -49.0345230400959$$
$$x_{3} = -61.6008936544551$$
$$x_{4} = 42.7513377329163$$
$$x_{5} = -99.3000054975326$$
$$x_{6} = -30.1849671185572$$
$$x_{7} = 5.05222588983881$$
$$x_{8} = -51.4964418747775$$
$$x_{9} = -101.761924332214$$
$$x_{10} = 20.0805153388795$$
$$x_{11} = -38.9300712604183$$
$$x_{12} = -55.3177083472755$$
$$x_{13} = 36.4681524257367$$
$$x_{14} = 86.7336348831734$$
$$x_{15} = -80.4504495759938$$
$$x_{16} = 11.3354111970184$$
$$x_{17} = 32.6468859532387$$
$$x_{18} = -36.4681524257367$$
$$x_{19} = -57.7796271819571$$
$$x_{20} = 93.016820190353$$
$$x_{21} = 23.9017818113776$$
$$x_{22} = -26.3637006460591$$
$$x_{23} = 76.6291831034958$$
$$x_{24} = -325.494676555998$$
$$x_{25} = -13.7973300316999$$
$$x_{26} = -32.6468859532387$$
$$x_{27} = 95.4787390250346$$
$$x_{28} = 30.1849671185572$$
$$x_{29} = -93.016820190353$$
$$x_{30} = -17.618596504198$$
$$x_{31} = 67.8840789616347$$
$$x_{32} = 17.618596504198$$
$$x_{33} = 82.9123684106754$$
$$x_{34} = 45.2132565675979$$
$$x_{35} = 51.4964418747775$$
$$x_{36} = 7.51414472452036$$
$$x_{37} = 61.6008936544551$$
$$x_{38} = -67.8840789616347$$
$$x_{39} = 64.0628124891366$$
$$x_{40} = 38.9300712604183$$
$$x_{41} = -64.0628124891366$$
$$x_{42} = 70.3459977963162$$
$$x_{43} = 13.7973300316999$$
$$x_{44} = 89.195553717855$$
$$x_{45} = -76.6291831034958$$
$$x_{46} = -1.23095941734077$$
$$x_{47} = -7.51414472452036$$
$$x_{48} = -82.9123684106754$$
$$x_{49} = 99.3000054975326$$
$$x_{50} = 74.1672642688143$$
$$x_{51} = 1.23095941734077$$
$$x_{52} = -11.3354111970184$$
$$x_{53} = 80.4504495759938$$
$$x_{54} = -23.9017818113776$$
$$x_{55} = -5.05222588983881$$
$$x_{56} = -20.0805153388795$$
$$x_{57} = -45.2132565675979$$
$$x_{58} = 26.3637006460591$$
$$x_{59} = 57.7796271819571$$
$$x_{60} = -95.4787390250346$$
$$x_{61} = 55.3177083472755$$
$$x_{62} = 49.0345230400959$$
$$x_{63} = -42.7513377329163$$
$$x_{64} = -89.195553717855$$
$$x_{65} = -70.3459977963162$$
$$x_{66} = -74.1672642688143$$
This roots
$$x_{24} = -325.494676555998$$
$$x_{9} = -101.761924332214$$
$$x_{5} = -99.3000054975326$$
$$x_{60} = -95.4787390250346$$
$$x_{29} = -93.016820190353$$
$$x_{64} = -89.195553717855$$
$$x_{1} = -86.7336348831734$$
$$x_{48} = -82.9123684106754$$
$$x_{15} = -80.4504495759938$$
$$x_{45} = -76.6291831034958$$
$$x_{66} = -74.1672642688143$$
$$x_{65} = -70.3459977963162$$
$$x_{38} = -67.8840789616347$$
$$x_{41} = -64.0628124891366$$
$$x_{3} = -61.6008936544551$$
$$x_{19} = -57.7796271819571$$
$$x_{12} = -55.3177083472755$$
$$x_{8} = -51.4964418747775$$
$$x_{2} = -49.0345230400959$$
$$x_{57} = -45.2132565675979$$
$$x_{63} = -42.7513377329163$$
$$x_{11} = -38.9300712604183$$
$$x_{18} = -36.4681524257367$$
$$x_{26} = -32.6468859532387$$
$$x_{6} = -30.1849671185572$$
$$x_{22} = -26.3637006460591$$
$$x_{54} = -23.9017818113776$$
$$x_{56} = -20.0805153388795$$
$$x_{30} = -17.618596504198$$
$$x_{25} = -13.7973300316999$$
$$x_{52} = -11.3354111970184$$
$$x_{47} = -7.51414472452036$$
$$x_{55} = -5.05222588983881$$
$$x_{46} = -1.23095941734077$$
$$x_{51} = 1.23095941734077$$
$$x_{7} = 5.05222588983881$$
$$x_{36} = 7.51414472452036$$
$$x_{16} = 11.3354111970184$$
$$x_{43} = 13.7973300316999$$
$$x_{32} = 17.618596504198$$
$$x_{10} = 20.0805153388795$$
$$x_{21} = 23.9017818113776$$
$$x_{58} = 26.3637006460591$$
$$x_{28} = 30.1849671185572$$
$$x_{17} = 32.6468859532387$$
$$x_{13} = 36.4681524257367$$
$$x_{40} = 38.9300712604183$$
$$x_{4} = 42.7513377329163$$
$$x_{34} = 45.2132565675979$$
$$x_{62} = 49.0345230400959$$
$$x_{35} = 51.4964418747775$$
$$x_{61} = 55.3177083472755$$
$$x_{59} = 57.7796271819571$$
$$x_{37} = 61.6008936544551$$
$$x_{39} = 64.0628124891366$$
$$x_{31} = 67.8840789616347$$
$$x_{42} = 70.3459977963162$$
$$x_{50} = 74.1672642688143$$
$$x_{23} = 76.6291831034958$$
$$x_{53} = 80.4504495759938$$
$$x_{33} = 82.9123684106754$$
$$x_{14} = 86.7336348831734$$
$$x_{44} = 89.195553717855$$
$$x_{20} = 93.016820190353$$
$$x_{27} = 95.4787390250346$$
$$x_{49} = 99.3000054975326$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{24}$$
For example, let's take the point
$$x_{0} = x_{24} - \frac{1}{10}$$
=
$$-325.494676555998 + - \frac{1}{10}$$
=
$$-325.594676555998$$
substitute to the expression
$$\cos{\left(t \right)} < \frac{1}{3}$$
$$\cos{\left(t \right)} < \frac{1}{3}$$
cos(t) < 1/3

Then
$$x < -325.494676555998$$
no execute
one of the solutions of our inequality is:
$$x > -325.494676555998 \wedge x < -101.761924332214$$
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       x24      x9      x5      x60      x29      x64      x1      x48      x15      x45      x66      x65      x38      x41      x3      x19      x12      x8      x2      x57      x63      x11      x18      x26      x6      x22      x54      x56      x30      x25      x52      x47      x55      x46      x51      x7      x36      x16      x43      x32      x10      x21      x58      x28      x17      x13      x40      x4      x34      x62      x35      x61      x59      x37      x39      x31      x42      x50      x23      x53      x33      x14      x44      x20      x27      x49

Other solutions will get with the changeover to the next point
etc.
The answer:
$$x > -325.494676555998 \wedge x < -101.761924332214$$
$$x > -99.3000054975326 \wedge x < -95.4787390250346$$
$$x > -93.016820190353 \wedge x < -89.195553717855$$
$$x > -86.7336348831734 \wedge x < -82.9123684106754$$
$$x > -80.4504495759938 \wedge x < -76.6291831034958$$
$$x > -74.1672642688143 \wedge x < -70.3459977963162$$
$$x > -67.8840789616347 \wedge x < -64.0628124891366$$
$$x > -61.6008936544551 \wedge x < -57.7796271819571$$
$$x > -55.3177083472755 \wedge x < -51.4964418747775$$
$$x > -49.0345230400959 \wedge x < -45.2132565675979$$
$$x > -42.7513377329163 \wedge x < -38.9300712604183$$
$$x > -36.4681524257367 \wedge x < -32.6468859532387$$
$$x > -30.1849671185572 \wedge x < -26.3637006460591$$
$$x > -23.9017818113776 \wedge x < -20.0805153388795$$
$$x > -17.618596504198 \wedge x < -13.7973300316999$$
$$x > -11.3354111970184 \wedge x < -7.51414472452036$$
$$x > -5.05222588983881 \wedge x < -1.23095941734077$$
$$x > 1.23095941734077 \wedge x < 5.05222588983881$$
$$x > 7.51414472452036 \wedge x < 11.3354111970184$$
$$x > 13.7973300316999 \wedge x < 17.618596504198$$
$$x > 20.0805153388795 \wedge x < 23.9017818113776$$
$$x > 26.3637006460591 \wedge x < 30.1849671185572$$
$$x > 32.6468859532387 \wedge x < 36.4681524257367$$
$$x > 38.9300712604183 \wedge x < 42.7513377329163$$
$$x > 45.2132565675979 \wedge x < 49.0345230400959$$
$$x > 51.4964418747775 \wedge x < 55.3177083472755$$
$$x > 57.7796271819571 \wedge x < 61.6008936544551$$
$$x > 64.0628124891366 \wedge x < 67.8840789616347$$
$$x > 70.3459977963162 \wedge x < 74.1672642688143$$
$$x > 76.6291831034958 \wedge x < 80.4504495759938$$
$$x > 82.9123684106754 \wedge x < 86.7336348831734$$
$$x > 89.195553717855 \wedge x < 93.016820190353$$
$$x > 95.4787390250346 \wedge x < 99.3000054975326$$
Rapid solution [src]
   /          /    ___\             /    ___\    \
And\t < - atan\2*\/ 2 / + 2*pi, atan\2*\/ 2 / < t/
$$t < - \operatorname{atan}{\left(2 \sqrt{2} \right)} + 2 \pi \wedge \operatorname{atan}{\left(2 \sqrt{2} \right)} < t$$
(atan(2*sqrt(2)) < t)∧(t < -atan(2*sqrt(2)) + 2*pi)
Rapid solution 2 [src]
     /    ___\        /    ___\        
(atan\2*\/ 2 /, - atan\2*\/ 2 / + 2*pi)
$$x\ in\ \left(\operatorname{atan}{\left(2 \sqrt{2} \right)}, - \operatorname{atan}{\left(2 \sqrt{2} \right)} + 2 \pi\right)$$
x in Interval.open(atan(2*sqrt(2)), -atan(2*sqrt(2)) + 2*pi)