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cost≤1/2 inequation

A inequation with variable

The solution

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cos(t) <= 1/2
$$\cos{\left(t \right)} \leq \frac{1}{2}$$
cos(t) <= 1/2
Detail solution
Given the inequality:
$$\cos{\left(t \right)} \leq \frac{1}{2}$$
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:
$$x_{1} = 38.7463093942741$$
$$x_{2} = 13.6135681655558$$
$$x_{3} = 11.5191730631626$$
$$x_{4} = -55.5014702134197$$
$$x_{5} = -30.3687289847013$$
$$x_{6} = -61.7846555205993$$
$$x_{7} = -86.9173967493176$$
$$x_{8} = 89.0117918517108$$
$$x_{9} = -51.3126800086333$$
$$x_{10} = 1.0471975511966$$
$$x_{11} = -68.0678408277789$$
$$x_{12} = 36.6519142918809$$
$$x_{13} = -70.162235930172$$
$$x_{14} = 93.2005820564972$$
$$x_{15} = -95.2949771588904$$
$$x_{16} = 49.2182849062401$$
$$x_{17} = 30.3687289847013$$
$$x_{18} = 17.8023583703422$$
$$x_{19} = -32.4631240870945$$
$$x_{20} = -99.4837673636768$$
$$x_{21} = 63.8790506229925$$
$$x_{22} = 42.9350995990605$$
$$x_{23} = -225.147473507269$$
$$x_{24} = -93.2005820564972$$
$$x_{25} = -17.8023583703422$$
$$x_{26} = 7.33038285837618$$
$$x_{27} = -11.5191730631626$$
$$x_{28} = 57.5958653158129$$
$$x_{29} = -42.9350995990605$$
$$x_{30} = -24.0855436775217$$
$$x_{31} = 70.162235930172$$
$$x_{32} = -36.6519142918809$$
$$x_{33} = -26.1799387799149$$
$$x_{34} = 19.8967534727354$$
$$x_{35} = -76.4454212373516$$
$$x_{36} = 76.4454212373516$$
$$x_{37} = -1.0471975511966$$
$$x_{38} = 1651.43053823704$$
$$x_{39} = 55.5014702134197$$
$$x_{40} = -5.23598775598299$$
$$x_{41} = 51.3126800086333$$
$$x_{42} = 45.0294947014537$$
$$x_{43} = 68.0678408277789$$
$$x_{44} = -45.0294947014537$$
$$x_{45} = -82.7286065445312$$
$$x_{46} = -19.8967534727354$$
$$x_{47} = -57.5958653158129$$
$$x_{48} = 74.3510261349584$$
$$x_{49} = -38.7463093942741$$
$$x_{50} = 80.634211442138$$
$$x_{51} = 99.4837673636768$$
$$x_{52} = -359.188760060433$$
$$x_{53} = 26.1799387799149$$
$$x_{54} = -63.8790506229925$$
$$x_{55} = 5.23598775598299$$
$$x_{56} = -89.0117918517108$$
$$x_{57} = 82.7286065445312$$
$$x_{58} = -13.6135681655558$$
$$x_{59} = -80.634211442138$$
$$x_{60} = -74.3510261349584$$
$$x_{61} = 86.9173967493176$$
$$x_{62} = 24.0855436775217$$
$$x_{63} = -49.2182849062401$$
$$x_{64} = 61.7846555205993$$
$$x_{65} = 95.2949771588904$$
$$x_{66} = 32.4631240870945$$
$$x_{67} = -7.33038285837618$$
$$x_{1} = 38.7463093942741$$
$$x_{2} = 13.6135681655558$$
$$x_{3} = 11.5191730631626$$
$$x_{4} = -55.5014702134197$$
$$x_{5} = -30.3687289847013$$
$$x_{6} = -61.7846555205993$$
$$x_{7} = -86.9173967493176$$
$$x_{8} = 89.0117918517108$$
$$x_{9} = -51.3126800086333$$
$$x_{10} = 1.0471975511966$$
$$x_{11} = -68.0678408277789$$
$$x_{12} = 36.6519142918809$$
$$x_{13} = -70.162235930172$$
$$x_{14} = 93.2005820564972$$
$$x_{15} = -95.2949771588904$$
$$x_{16} = 49.2182849062401$$
$$x_{17} = 30.3687289847013$$
$$x_{18} = 17.8023583703422$$
$$x_{19} = -32.4631240870945$$
$$x_{20} = -99.4837673636768$$
$$x_{21} = 63.8790506229925$$
$$x_{22} = 42.9350995990605$$
$$x_{23} = -225.147473507269$$
$$x_{24} = -93.2005820564972$$
$$x_{25} = -17.8023583703422$$
$$x_{26} = 7.33038285837618$$
$$x_{27} = -11.5191730631626$$
$$x_{28} = 57.5958653158129$$
$$x_{29} = -42.9350995990605$$
$$x_{30} = -24.0855436775217$$
$$x_{31} = 70.162235930172$$
$$x_{32} = -36.6519142918809$$
$$x_{33} = -26.1799387799149$$
$$x_{34} = 19.8967534727354$$
$$x_{35} = -76.4454212373516$$
$$x_{36} = 76.4454212373516$$
$$x_{37} = -1.0471975511966$$
$$x_{38} = 1651.43053823704$$
$$x_{39} = 55.5014702134197$$
$$x_{40} = -5.23598775598299$$
$$x_{41} = 51.3126800086333$$
$$x_{42} = 45.0294947014537$$
$$x_{43} = 68.0678408277789$$
$$x_{44} = -45.0294947014537$$
$$x_{45} = -82.7286065445312$$
$$x_{46} = -19.8967534727354$$
$$x_{47} = -57.5958653158129$$
$$x_{48} = 74.3510261349584$$
$$x_{49} = -38.7463093942741$$
$$x_{50} = 80.634211442138$$
$$x_{51} = 99.4837673636768$$
$$x_{52} = -359.188760060433$$
$$x_{53} = 26.1799387799149$$
$$x_{54} = -63.8790506229925$$
$$x_{55} = 5.23598775598299$$
$$x_{56} = -89.0117918517108$$
$$x_{57} = 82.7286065445312$$
$$x_{58} = -13.6135681655558$$
$$x_{59} = -80.634211442138$$
$$x_{60} = -74.3510261349584$$
$$x_{61} = 86.9173967493176$$
$$x_{62} = 24.0855436775217$$
$$x_{63} = -49.2182849062401$$
$$x_{64} = 61.7846555205993$$
$$x_{65} = 95.2949771588904$$
$$x_{66} = 32.4631240870945$$
$$x_{67} = -7.33038285837618$$
This roots
$$x_{52} = -359.188760060433$$
$$x_{23} = -225.147473507269$$
$$x_{20} = -99.4837673636768$$
$$x_{15} = -95.2949771588904$$
$$x_{24} = -93.2005820564972$$
$$x_{56} = -89.0117918517108$$
$$x_{7} = -86.9173967493176$$
$$x_{45} = -82.7286065445312$$
$$x_{59} = -80.634211442138$$
$$x_{35} = -76.4454212373516$$
$$x_{60} = -74.3510261349584$$
$$x_{13} = -70.162235930172$$
$$x_{11} = -68.0678408277789$$
$$x_{54} = -63.8790506229925$$
$$x_{6} = -61.7846555205993$$
$$x_{47} = -57.5958653158129$$
$$x_{4} = -55.5014702134197$$
$$x_{9} = -51.3126800086333$$
$$x_{63} = -49.2182849062401$$
$$x_{44} = -45.0294947014537$$
$$x_{29} = -42.9350995990605$$
$$x_{49} = -38.7463093942741$$
$$x_{32} = -36.6519142918809$$
$$x_{19} = -32.4631240870945$$
$$x_{5} = -30.3687289847013$$
$$x_{33} = -26.1799387799149$$
$$x_{30} = -24.0855436775217$$
$$x_{46} = -19.8967534727354$$
$$x_{25} = -17.8023583703422$$
$$x_{58} = -13.6135681655558$$
$$x_{27} = -11.5191730631626$$
$$x_{67} = -7.33038285837618$$
$$x_{40} = -5.23598775598299$$
$$x_{37} = -1.0471975511966$$
$$x_{10} = 1.0471975511966$$
$$x_{55} = 5.23598775598299$$
$$x_{26} = 7.33038285837618$$
$$x_{3} = 11.5191730631626$$
$$x_{2} = 13.6135681655558$$
$$x_{18} = 17.8023583703422$$
$$x_{34} = 19.8967534727354$$
$$x_{62} = 24.0855436775217$$
$$x_{53} = 26.1799387799149$$
$$x_{17} = 30.3687289847013$$
$$x_{66} = 32.4631240870945$$
$$x_{12} = 36.6519142918809$$
$$x_{1} = 38.7463093942741$$
$$x_{22} = 42.9350995990605$$
$$x_{42} = 45.0294947014537$$
$$x_{16} = 49.2182849062401$$
$$x_{41} = 51.3126800086333$$
$$x_{39} = 55.5014702134197$$
$$x_{28} = 57.5958653158129$$
$$x_{64} = 61.7846555205993$$
$$x_{21} = 63.8790506229925$$
$$x_{43} = 68.0678408277789$$
$$x_{31} = 70.162235930172$$
$$x_{48} = 74.3510261349584$$
$$x_{36} = 76.4454212373516$$
$$x_{50} = 80.634211442138$$
$$x_{57} = 82.7286065445312$$
$$x_{61} = 86.9173967493176$$
$$x_{8} = 89.0117918517108$$
$$x_{14} = 93.2005820564972$$
$$x_{65} = 95.2949771588904$$
$$x_{51} = 99.4837673636768$$
$$x_{38} = 1651.43053823704$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} \leq x_{52}$$
For example, let's take the point
$$x_{0} = x_{52} - \frac{1}{10}$$
=
$$-359.188760060433 + - \frac{1}{10}$$
=
$$-359.288760060433$$
substitute to the expression
$$\cos{\left(t \right)} \leq \frac{1}{2}$$
$$\cos{\left(t \right)} \leq \frac{1}{2}$$
cos(t) <= 1/2

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

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