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cos(t)<0,5 inequation

A inequation with variable

The solution

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cos(t) < 1/2
$$\cos{\left(t \right)} < \frac{1}{2}$$
cos(t) < 1/2
Detail solution
Given the inequality:
$$\cos{\left(t \right)} < \frac{1}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$\cos{\left(t \right)} = \frac{1}{2}$$
Solve:
Given the equation
$$\cos{\left(t \right)} = \frac{1}{2}$$
transform
$$\cos{\left(t \right)} - \frac{1}{2} = 0$$
$$\cos{\left(t \right)} - \frac{1}{2} = 0$$
Do replacement
$$w = \cos{\left(t \right)}$$
Move free summands (without w)
from left part to right part, we given:
$$w = \frac{1}{2}$$
We get the answer: w = 1/2
do backward replacement
$$\cos{\left(t \right)} = w$$
substitute w:
$$x_{1} = -61.7846555205993$$
$$x_{2} = 17.8023583703422$$
$$x_{3} = 99.4837673636768$$
$$x_{4} = -225.147473507269$$
$$x_{5} = 80.634211442138$$
$$x_{6} = 63.8790506229925$$
$$x_{7} = -86.9173967493176$$
$$x_{8} = 95.2949771588904$$
$$x_{9} = -45.0294947014537$$
$$x_{10} = 70.162235930172$$
$$x_{11} = -26.1799387799149$$
$$x_{12} = -99.4837673636768$$
$$x_{13} = -38.7463093942741$$
$$x_{14} = 13.6135681655558$$
$$x_{15} = 24.0855436775217$$
$$x_{16} = 82.7286065445312$$
$$x_{17} = -17.8023583703422$$
$$x_{18} = 93.2005820564972$$
$$x_{19} = -80.634211442138$$
$$x_{20} = -42.9350995990605$$
$$x_{21} = 68.0678408277789$$
$$x_{22} = -49.2182849062401$$
$$x_{23} = -13.6135681655558$$
$$x_{24} = 32.4631240870945$$
$$x_{25} = -57.5958653158129$$
$$x_{26} = 74.3510261349584$$
$$x_{27} = 86.9173967493176$$
$$x_{28} = -359.188760060433$$
$$x_{29} = -55.5014702134197$$
$$x_{30} = -68.0678408277789$$
$$x_{31} = 51.3126800086333$$
$$x_{32} = 36.6519142918809$$
$$x_{33} = 7.33038285837618$$
$$x_{34} = 19.8967534727354$$
$$x_{35} = 76.4454212373516$$
$$x_{36} = 38.7463093942741$$
$$x_{37} = -32.4631240870945$$
$$x_{38} = 55.5014702134197$$
$$x_{39} = -51.3126800086333$$
$$x_{40} = -5.23598775598299$$
$$x_{41} = 30.3687289847013$$
$$x_{42} = -19.8967534727354$$
$$x_{43} = 57.5958653158129$$
$$x_{44} = 61.7846555205993$$
$$x_{45} = 5.23598775598299$$
$$x_{46} = -11.5191730631626$$
$$x_{47} = 1651.43053823704$$
$$x_{48} = -7.33038285837618$$
$$x_{49} = -1.0471975511966$$
$$x_{50} = -30.3687289847013$$
$$x_{51} = -70.162235930172$$
$$x_{52} = -93.2005820564972$$
$$x_{53} = -24.0855436775217$$
$$x_{54} = -95.2949771588904$$
$$x_{55} = 11.5191730631626$$
$$x_{56} = -89.0117918517108$$
$$x_{57} = -63.8790506229925$$
$$x_{58} = 49.2182849062401$$
$$x_{59} = 42.9350995990605$$
$$x_{60} = -76.4454212373516$$
$$x_{61} = 45.0294947014537$$
$$x_{62} = 1.0471975511966$$
$$x_{63} = 26.1799387799149$$
$$x_{64} = 89.0117918517108$$
$$x_{65} = -36.6519142918809$$
$$x_{66} = -82.7286065445312$$
$$x_{67} = -74.3510261349584$$
$$x_{1} = -61.7846555205993$$
$$x_{2} = 17.8023583703422$$
$$x_{3} = 99.4837673636768$$
$$x_{4} = -225.147473507269$$
$$x_{5} = 80.634211442138$$
$$x_{6} = 63.8790506229925$$
$$x_{7} = -86.9173967493176$$
$$x_{8} = 95.2949771588904$$
$$x_{9} = -45.0294947014537$$
$$x_{10} = 70.162235930172$$
$$x_{11} = -26.1799387799149$$
$$x_{12} = -99.4837673636768$$
$$x_{13} = -38.7463093942741$$
$$x_{14} = 13.6135681655558$$
$$x_{15} = 24.0855436775217$$
$$x_{16} = 82.7286065445312$$
$$x_{17} = -17.8023583703422$$
$$x_{18} = 93.2005820564972$$
$$x_{19} = -80.634211442138$$
$$x_{20} = -42.9350995990605$$
$$x_{21} = 68.0678408277789$$
$$x_{22} = -49.2182849062401$$
$$x_{23} = -13.6135681655558$$
$$x_{24} = 32.4631240870945$$
$$x_{25} = -57.5958653158129$$
$$x_{26} = 74.3510261349584$$
$$x_{27} = 86.9173967493176$$
$$x_{28} = -359.188760060433$$
$$x_{29} = -55.5014702134197$$
$$x_{30} = -68.0678408277789$$
$$x_{31} = 51.3126800086333$$
$$x_{32} = 36.6519142918809$$
$$x_{33} = 7.33038285837618$$
$$x_{34} = 19.8967534727354$$
$$x_{35} = 76.4454212373516$$
$$x_{36} = 38.7463093942741$$
$$x_{37} = -32.4631240870945$$
$$x_{38} = 55.5014702134197$$
$$x_{39} = -51.3126800086333$$
$$x_{40} = -5.23598775598299$$
$$x_{41} = 30.3687289847013$$
$$x_{42} = -19.8967534727354$$
$$x_{43} = 57.5958653158129$$
$$x_{44} = 61.7846555205993$$
$$x_{45} = 5.23598775598299$$
$$x_{46} = -11.5191730631626$$
$$x_{47} = 1651.43053823704$$
$$x_{48} = -7.33038285837618$$
$$x_{49} = -1.0471975511966$$
$$x_{50} = -30.3687289847013$$
$$x_{51} = -70.162235930172$$
$$x_{52} = -93.2005820564972$$
$$x_{53} = -24.0855436775217$$
$$x_{54} = -95.2949771588904$$
$$x_{55} = 11.5191730631626$$
$$x_{56} = -89.0117918517108$$
$$x_{57} = -63.8790506229925$$
$$x_{58} = 49.2182849062401$$
$$x_{59} = 42.9350995990605$$
$$x_{60} = -76.4454212373516$$
$$x_{61} = 45.0294947014537$$
$$x_{62} = 1.0471975511966$$
$$x_{63} = 26.1799387799149$$
$$x_{64} = 89.0117918517108$$
$$x_{65} = -36.6519142918809$$
$$x_{66} = -82.7286065445312$$
$$x_{67} = -74.3510261349584$$
This roots
$$x_{28} = -359.188760060433$$
$$x_{4} = -225.147473507269$$
$$x_{12} = -99.4837673636768$$
$$x_{54} = -95.2949771588904$$
$$x_{52} = -93.2005820564972$$
$$x_{56} = -89.0117918517108$$
$$x_{7} = -86.9173967493176$$
$$x_{66} = -82.7286065445312$$
$$x_{19} = -80.634211442138$$
$$x_{60} = -76.4454212373516$$
$$x_{67} = -74.3510261349584$$
$$x_{51} = -70.162235930172$$
$$x_{30} = -68.0678408277789$$
$$x_{57} = -63.8790506229925$$
$$x_{1} = -61.7846555205993$$
$$x_{25} = -57.5958653158129$$
$$x_{29} = -55.5014702134197$$
$$x_{39} = -51.3126800086333$$
$$x_{22} = -49.2182849062401$$
$$x_{9} = -45.0294947014537$$
$$x_{20} = -42.9350995990605$$
$$x_{13} = -38.7463093942741$$
$$x_{65} = -36.6519142918809$$
$$x_{37} = -32.4631240870945$$
$$x_{50} = -30.3687289847013$$
$$x_{11} = -26.1799387799149$$
$$x_{53} = -24.0855436775217$$
$$x_{42} = -19.8967534727354$$
$$x_{17} = -17.8023583703422$$
$$x_{23} = -13.6135681655558$$
$$x_{46} = -11.5191730631626$$
$$x_{48} = -7.33038285837618$$
$$x_{40} = -5.23598775598299$$
$$x_{49} = -1.0471975511966$$
$$x_{62} = 1.0471975511966$$
$$x_{45} = 5.23598775598299$$
$$x_{33} = 7.33038285837618$$
$$x_{55} = 11.5191730631626$$
$$x_{14} = 13.6135681655558$$
$$x_{2} = 17.8023583703422$$
$$x_{34} = 19.8967534727354$$
$$x_{15} = 24.0855436775217$$
$$x_{63} = 26.1799387799149$$
$$x_{41} = 30.3687289847013$$
$$x_{24} = 32.4631240870945$$
$$x_{32} = 36.6519142918809$$
$$x_{36} = 38.7463093942741$$
$$x_{59} = 42.9350995990605$$
$$x_{61} = 45.0294947014537$$
$$x_{58} = 49.2182849062401$$
$$x_{31} = 51.3126800086333$$
$$x_{38} = 55.5014702134197$$
$$x_{43} = 57.5958653158129$$
$$x_{44} = 61.7846555205993$$
$$x_{6} = 63.8790506229925$$
$$x_{21} = 68.0678408277789$$
$$x_{10} = 70.162235930172$$
$$x_{26} = 74.3510261349584$$
$$x_{35} = 76.4454212373516$$
$$x_{5} = 80.634211442138$$
$$x_{16} = 82.7286065445312$$
$$x_{27} = 86.9173967493176$$
$$x_{64} = 89.0117918517108$$
$$x_{18} = 93.2005820564972$$
$$x_{8} = 95.2949771588904$$
$$x_{3} = 99.4837673636768$$
$$x_{47} = 1651.43053823704$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{28}$$
For example, let's take the point
$$x_{0} = x_{28} - \frac{1}{10}$$
=
$$-359.188760060433 + - \frac{1}{10}$$
=
$$-359.288760060433$$
substitute to the expression
$$\cos{\left(t \right)} < \frac{1}{2}$$
$$\cos{\left(t \right)} < \frac{1}{2}$$
cos(t) < 1/2

Then
$$x < -359.188760060433$$
no execute
one of the solutions of our inequality is:
$$x > -359.188760060433 \wedge x < -225.147473507269$$
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        /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /
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       x28      x4      x12      x54      x52      x56      x7      x66      x19      x60      x67      x51      x30      x57      x1      x25      x29      x39      x22      x9      x20      x13      x65      x37      x50      x11      x53      x42      x17      x23      x46      x48      x40      x49      x62      x45      x33      x55      x14      x2      x34      x15      x63      x41      x24      x32      x36      x59      x61      x58      x31      x38      x43      x44      x6      x21      x10      x26      x35      x5      x16      x27      x64      x18      x8      x3      x47

Other solutions will get with the changeover to the next point
etc.
The answer:
$$x > -359.188760060433 \wedge x < -225.147473507269$$
$$x > -99.4837673636768 \wedge x < -95.2949771588904$$
$$x > -93.2005820564972 \wedge x < -89.0117918517108$$
$$x > -86.9173967493176 \wedge x < -82.7286065445312$$
$$x > -80.634211442138 \wedge x < -76.4454212373516$$
$$x > -74.3510261349584 \wedge x < -70.162235930172$$
$$x > -68.0678408277789 \wedge x < -63.8790506229925$$
$$x > -61.7846555205993 \wedge x < -57.5958653158129$$
$$x > -55.5014702134197 \wedge x < -51.3126800086333$$
$$x > -49.2182849062401 \wedge x < -45.0294947014537$$
$$x > -42.9350995990605 \wedge x < -38.7463093942741$$
$$x > -36.6519142918809 \wedge x < -32.4631240870945$$
$$x > -30.3687289847013 \wedge x < -26.1799387799149$$
$$x > -24.0855436775217 \wedge x < -19.8967534727354$$
$$x > -17.8023583703422 \wedge x < -13.6135681655558$$
$$x > -11.5191730631626 \wedge x < -7.33038285837618$$
$$x > -5.23598775598299 \wedge x < -1.0471975511966$$
$$x > 1.0471975511966 \wedge x < 5.23598775598299$$
$$x > 7.33038285837618 \wedge x < 11.5191730631626$$
$$x > 13.6135681655558 \wedge x < 17.8023583703422$$
$$x > 19.8967534727354 \wedge x < 24.0855436775217$$
$$x > 26.1799387799149 \wedge x < 30.3687289847013$$
$$x > 32.4631240870945 \wedge x < 36.6519142918809$$
$$x > 38.7463093942741 \wedge x < 42.9350995990605$$
$$x > 45.0294947014537 \wedge x < 49.2182849062401$$
$$x > 51.3126800086333 \wedge x < 55.5014702134197$$
$$x > 57.5958653158129 \wedge x < 61.7846555205993$$
$$x > 63.8790506229925 \wedge x < 68.0678408277789$$
$$x > 70.162235930172 \wedge x < 74.3510261349584$$
$$x > 76.4454212373516 \wedge x < 80.634211442138$$
$$x > 82.7286065445312 \wedge x < 86.9173967493176$$
$$x > 89.0117918517108 \wedge x < 93.2005820564972$$
$$x > 95.2949771588904 \wedge x < 99.4837673636768$$
$$x > 1651.43053823704$$
Rapid solution [src]
   /pi          5*pi\
And|-- < t, t < ----|
   \3            3  /
$$\frac{\pi}{3} < t \wedge t < \frac{5 \pi}{3}$$
(pi/3 < t)∧(t < 5*pi/3)
Rapid solution 2 [src]
 pi  5*pi 
(--, ----)
 3    3   
$$x\ in\ \left(\frac{\pi}{3}, \frac{5 \pi}{3}\right)$$
x in Interval.open(pi/3, 5*pi/3)