Mister Exam

Other calculators

abs(cos(x))<1/2 inequation

A inequation with variable

The solution

You have entered [src]
|cos(x)| < 1/2
$$\left|{\cos{\left(x \right)}}\right| < \frac{1}{2}$$
Abs(cos(x)) < 1/2
Detail solution
Given the inequality:
$$\left|{\cos{\left(x \right)}}\right| < \frac{1}{2}$$
To solve this inequality, we must first solve the corresponding equation:
$$\left|{\cos{\left(x \right)}}\right| = \frac{1}{2}$$
Solve:
Given the equation
$$\left|{\cos{\left(x \right)}}\right| = \frac{1}{2}$$
transform
$$\left|{\cos{\left(x \right)}}\right| - \frac{1}{2} = 0$$
$$\left|{\cos{\left(x \right)}}\right| - \frac{1}{2} = 0$$
Do replacement
$$w = \left|{\cos{\left(x \right)}}\right|$$
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
$$\left|{\cos{\left(x \right)}}\right| = w$$
substitute w:
$$x_{1} = 85.870199198121$$
$$x_{2} = 74.3510261349584$$
$$x_{3} = -673.348025419412$$
$$x_{4} = -41.8879020478639$$
$$x_{5} = 55.5014702134197$$
$$x_{6} = -68.0678408277789$$
$$x_{7} = -77.4926187885482$$
$$x_{8} = 269.129770657526$$
$$x_{9} = -90.0589894029074$$
$$x_{10} = -71.2094334813686$$
$$x_{11} = -99.4837673636768$$
$$x_{12} = 52.3598775598299$$
$$x_{13} = -42.9350995990605$$
$$x_{14} = -48.1710873550435$$
$$x_{15} = -46.0766922526503$$
$$x_{16} = -2.0943951023932$$
$$x_{17} = -92.1533845053006$$
$$x_{18} = -52.3598775598299$$
$$x_{19} = 70.162235930172$$
$$x_{20} = 4.18879020478639$$
$$x_{21} = -74.3510261349584$$
$$x_{22} = 41.8879020478639$$
$$x_{23} = -70.162235930172$$
$$x_{24} = -13.6135681655558$$
$$x_{25} = 33.5103216382911$$
$$x_{26} = -85.870199198121$$
$$x_{27} = 48.1710873550435$$
$$x_{28} = -17.8023583703422$$
$$x_{29} = 10.471975511966$$
$$x_{30} = -35.6047167406843$$
$$x_{31} = 82.7286065445312$$
$$x_{32} = 3803.42150594604$$
$$x_{33} = -55.5014702134197$$
$$x_{34} = 46.0766922526503$$
$$x_{35} = -83.7758040957278$$
$$x_{36} = 63.8790506229925$$
$$x_{37} = 77.4926187885482$$
$$x_{38} = 39.7935069454707$$
$$x_{39} = -79.5870138909414$$
$$x_{40} = 96.342174710087$$
$$x_{41} = -60.7374579694027$$
$$x_{42} = -30.3687289847013$$
$$x_{43} = -54.4542726622231$$
$$x_{44} = 83.7758040957278$$
$$x_{45} = -19.8967534727354$$
$$x_{46} = 8.37758040957278$$
$$x_{47} = -32.4631240870945$$
$$x_{48} = -33.5103216382911$$
$$x_{49} = -11.5191730631626$$
$$x_{50} = -61.7846555205993$$
$$x_{51} = -93.2005820564972$$
$$x_{52} = -24.0855436775217$$
$$x_{53} = -10.471975511966$$
$$x_{54} = -39.7935069454707$$
$$x_{55} = -5.23598775598299$$
$$x_{56} = 2.0943951023932$$
$$x_{57} = 54.4542726622231$$
$$x_{58} = 17.8023583703422$$
$$x_{59} = -76.4454212373516$$
$$x_{60} = -26.1799387799149$$
$$x_{61} = 98.4365698124802$$
$$x_{62} = 24.0855436775217$$
$$x_{63} = 99.4837673636768$$
$$x_{64} = -27.2271363311115$$
$$x_{65} = 275.412955964705$$
$$x_{66} = 30.3687289847013$$
$$x_{67} = 92.1533845053006$$
$$x_{68} = -98.4365698124802$$
$$x_{69} = 38.7463093942741$$
$$x_{70} = 32.4631240870945$$
$$x_{71} = 61.7846555205993$$
$$x_{72} = -57.5958653158129$$
$$x_{73} = -63.8790506229925$$
$$x_{74} = 11.5191730631626$$
$$x_{75} = -4.18879020478639$$
$$x_{76} = 68.0678408277789$$
$$x_{77} = -49.2182849062401$$
$$x_{78} = 26.1799387799149$$
$$x_{79} = 76.4454212373516$$
$$x_{80} = 90.0589894029074$$
$$x_{81} = 60.7374579694027$$
$$x_{82} = 16.7551608191456$$
$$x_{83} = 19.8967534727354$$
$$x_{84} = -96.342174710087$$
$$x_{1} = 85.870199198121$$
$$x_{2} = 74.3510261349584$$
$$x_{3} = -673.348025419412$$
$$x_{4} = -41.8879020478639$$
$$x_{5} = 55.5014702134197$$
$$x_{6} = -68.0678408277789$$
$$x_{7} = -77.4926187885482$$
$$x_{8} = 269.129770657526$$
$$x_{9} = -90.0589894029074$$
$$x_{10} = -71.2094334813686$$
$$x_{11} = -99.4837673636768$$
$$x_{12} = 52.3598775598299$$
$$x_{13} = -42.9350995990605$$
$$x_{14} = -48.1710873550435$$
$$x_{15} = -46.0766922526503$$
$$x_{16} = -2.0943951023932$$
$$x_{17} = -92.1533845053006$$
$$x_{18} = -52.3598775598299$$
$$x_{19} = 70.162235930172$$
$$x_{20} = 4.18879020478639$$
$$x_{21} = -74.3510261349584$$
$$x_{22} = 41.8879020478639$$
$$x_{23} = -70.162235930172$$
$$x_{24} = -13.6135681655558$$
$$x_{25} = 33.5103216382911$$
$$x_{26} = -85.870199198121$$
$$x_{27} = 48.1710873550435$$
$$x_{28} = -17.8023583703422$$
$$x_{29} = 10.471975511966$$
$$x_{30} = -35.6047167406843$$
$$x_{31} = 82.7286065445312$$
$$x_{32} = 3803.42150594604$$
$$x_{33} = -55.5014702134197$$
$$x_{34} = 46.0766922526503$$
$$x_{35} = -83.7758040957278$$
$$x_{36} = 63.8790506229925$$
$$x_{37} = 77.4926187885482$$
$$x_{38} = 39.7935069454707$$
$$x_{39} = -79.5870138909414$$
$$x_{40} = 96.342174710087$$
$$x_{41} = -60.7374579694027$$
$$x_{42} = -30.3687289847013$$
$$x_{43} = -54.4542726622231$$
$$x_{44} = 83.7758040957278$$
$$x_{45} = -19.8967534727354$$
$$x_{46} = 8.37758040957278$$
$$x_{47} = -32.4631240870945$$
$$x_{48} = -33.5103216382911$$
$$x_{49} = -11.5191730631626$$
$$x_{50} = -61.7846555205993$$
$$x_{51} = -93.2005820564972$$
$$x_{52} = -24.0855436775217$$
$$x_{53} = -10.471975511966$$
$$x_{54} = -39.7935069454707$$
$$x_{55} = -5.23598775598299$$
$$x_{56} = 2.0943951023932$$
$$x_{57} = 54.4542726622231$$
$$x_{58} = 17.8023583703422$$
$$x_{59} = -76.4454212373516$$
$$x_{60} = -26.1799387799149$$
$$x_{61} = 98.4365698124802$$
$$x_{62} = 24.0855436775217$$
$$x_{63} = 99.4837673636768$$
$$x_{64} = -27.2271363311115$$
$$x_{65} = 275.412955964705$$
$$x_{66} = 30.3687289847013$$
$$x_{67} = 92.1533845053006$$
$$x_{68} = -98.4365698124802$$
$$x_{69} = 38.7463093942741$$
$$x_{70} = 32.4631240870945$$
$$x_{71} = 61.7846555205993$$
$$x_{72} = -57.5958653158129$$
$$x_{73} = -63.8790506229925$$
$$x_{74} = 11.5191730631626$$
$$x_{75} = -4.18879020478639$$
$$x_{76} = 68.0678408277789$$
$$x_{77} = -49.2182849062401$$
$$x_{78} = 26.1799387799149$$
$$x_{79} = 76.4454212373516$$
$$x_{80} = 90.0589894029074$$
$$x_{81} = 60.7374579694027$$
$$x_{82} = 16.7551608191456$$
$$x_{83} = 19.8967534727354$$
$$x_{84} = -96.342174710087$$
This roots
$$x_{3} = -673.348025419412$$
$$x_{11} = -99.4837673636768$$
$$x_{68} = -98.4365698124802$$
$$x_{84} = -96.342174710087$$
$$x_{51} = -93.2005820564972$$
$$x_{17} = -92.1533845053006$$
$$x_{9} = -90.0589894029074$$
$$x_{26} = -85.870199198121$$
$$x_{35} = -83.7758040957278$$
$$x_{39} = -79.5870138909414$$
$$x_{7} = -77.4926187885482$$
$$x_{59} = -76.4454212373516$$
$$x_{21} = -74.3510261349584$$
$$x_{10} = -71.2094334813686$$
$$x_{23} = -70.162235930172$$
$$x_{6} = -68.0678408277789$$
$$x_{73} = -63.8790506229925$$
$$x_{50} = -61.7846555205993$$
$$x_{41} = -60.7374579694027$$
$$x_{72} = -57.5958653158129$$
$$x_{33} = -55.5014702134197$$
$$x_{43} = -54.4542726622231$$
$$x_{18} = -52.3598775598299$$
$$x_{77} = -49.2182849062401$$
$$x_{14} = -48.1710873550435$$
$$x_{15} = -46.0766922526503$$
$$x_{13} = -42.9350995990605$$
$$x_{4} = -41.8879020478639$$
$$x_{54} = -39.7935069454707$$
$$x_{30} = -35.6047167406843$$
$$x_{48} = -33.5103216382911$$
$$x_{47} = -32.4631240870945$$
$$x_{42} = -30.3687289847013$$
$$x_{64} = -27.2271363311115$$
$$x_{60} = -26.1799387799149$$
$$x_{52} = -24.0855436775217$$
$$x_{45} = -19.8967534727354$$
$$x_{28} = -17.8023583703422$$
$$x_{24} = -13.6135681655558$$
$$x_{49} = -11.5191730631626$$
$$x_{53} = -10.471975511966$$
$$x_{55} = -5.23598775598299$$
$$x_{75} = -4.18879020478639$$
$$x_{16} = -2.0943951023932$$
$$x_{56} = 2.0943951023932$$
$$x_{20} = 4.18879020478639$$
$$x_{46} = 8.37758040957278$$
$$x_{29} = 10.471975511966$$
$$x_{74} = 11.5191730631626$$
$$x_{82} = 16.7551608191456$$
$$x_{58} = 17.8023583703422$$
$$x_{83} = 19.8967534727354$$
$$x_{62} = 24.0855436775217$$
$$x_{78} = 26.1799387799149$$
$$x_{66} = 30.3687289847013$$
$$x_{70} = 32.4631240870945$$
$$x_{25} = 33.5103216382911$$
$$x_{69} = 38.7463093942741$$
$$x_{38} = 39.7935069454707$$
$$x_{22} = 41.8879020478639$$
$$x_{34} = 46.0766922526503$$
$$x_{27} = 48.1710873550435$$
$$x_{12} = 52.3598775598299$$
$$x_{57} = 54.4542726622231$$
$$x_{5} = 55.5014702134197$$
$$x_{81} = 60.7374579694027$$
$$x_{71} = 61.7846555205993$$
$$x_{36} = 63.8790506229925$$
$$x_{76} = 68.0678408277789$$
$$x_{19} = 70.162235930172$$
$$x_{2} = 74.3510261349584$$
$$x_{79} = 76.4454212373516$$
$$x_{37} = 77.4926187885482$$
$$x_{31} = 82.7286065445312$$
$$x_{44} = 83.7758040957278$$
$$x_{1} = 85.870199198121$$
$$x_{80} = 90.0589894029074$$
$$x_{67} = 92.1533845053006$$
$$x_{40} = 96.342174710087$$
$$x_{61} = 98.4365698124802$$
$$x_{63} = 99.4837673636768$$
$$x_{8} = 269.129770657526$$
$$x_{65} = 275.412955964705$$
$$x_{32} = 3803.42150594604$$
is the points with change the sign of the inequality expression.
First define with the sign to the leftmost point:
$$x_{0} < x_{3}$$
For example, let's take the point
$$x_{0} = x_{3} - \frac{1}{10}$$
=
$$-673.348025419412 + - \frac{1}{10}$$
=
$$-673.448025419412$$
substitute to the expression
$$\left|{\cos{\left(x \right)}}\right| < \frac{1}{2}$$
$$\left|{\cos{\left(-673.448025419412 \right)}}\right| < \frac{1}{2}$$
0.411043807676242 < 1/2

one of the solutions of our inequality is:
$$x < -673.348025419412$$
 _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____           _____          
      \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /     \         /
-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------ο-------
       x3      x11      x68      x84      x51      x17      x9      x26      x35      x39      x7      x59      x21      x10      x23      x6      x73      x50      x41      x72      x33      x43      x18      x77      x14      x15      x13      x4      x54      x30      x48      x47      x42      x64      x60      x52      x45      x28      x24      x49      x53      x55      x75      x16      x56      x20      x46      x29      x74      x82      x58      x83      x62      x78      x66      x70      x25      x69      x38      x22      x34      x27      x12      x57      x5      x81      x71      x36      x76      x19      x2      x79      x37      x31      x44      x1      x80      x67      x40      x61      x63      x8      x65      x32

Other solutions will get with the changeover to the next point
etc.
The answer:
$$x < -673.348025419412$$
$$x > -99.4837673636768 \wedge x < -98.4365698124802$$
$$x > -96.342174710087 \wedge x < -93.2005820564972$$
$$x > -92.1533845053006 \wedge x < -90.0589894029074$$
$$x > -85.870199198121 \wedge x < -83.7758040957278$$
$$x > -79.5870138909414 \wedge x < -77.4926187885482$$
$$x > -76.4454212373516 \wedge x < -74.3510261349584$$
$$x > -71.2094334813686 \wedge x < -70.162235930172$$
$$x > -68.0678408277789 \wedge x < -63.8790506229925$$
$$x > -61.7846555205993 \wedge x < -60.7374579694027$$
$$x > -57.5958653158129 \wedge x < -55.5014702134197$$
$$x > -54.4542726622231 \wedge x < -52.3598775598299$$
$$x > -49.2182849062401 \wedge x < -48.1710873550435$$
$$x > -46.0766922526503 \wedge x < -42.9350995990605$$
$$x > -41.8879020478639 \wedge x < -39.7935069454707$$
$$x > -35.6047167406843 \wedge x < -33.5103216382911$$
$$x > -32.4631240870945 \wedge x < -30.3687289847013$$
$$x > -27.2271363311115 \wedge x < -26.1799387799149$$
$$x > -24.0855436775217 \wedge x < -19.8967534727354$$
$$x > -17.8023583703422 \wedge x < -13.6135681655558$$
$$x > -11.5191730631626 \wedge x < -10.471975511966$$
$$x > -5.23598775598299 \wedge x < -4.18879020478639$$
$$x > -2.0943951023932 \wedge x < 2.0943951023932$$
$$x > 4.18879020478639 \wedge x < 8.37758040957278$$
$$x > 10.471975511966 \wedge x < 11.5191730631626$$
$$x > 16.7551608191456 \wedge x < 17.8023583703422$$
$$x > 19.8967534727354 \wedge x < 24.0855436775217$$
$$x > 26.1799387799149 \wedge x < 30.3687289847013$$
$$x > 32.4631240870945 \wedge x < 33.5103216382911$$
$$x > 38.7463093942741 \wedge x < 39.7935069454707$$
$$x > 41.8879020478639 \wedge x < 46.0766922526503$$
$$x > 48.1710873550435 \wedge x < 52.3598775598299$$
$$x > 54.4542726622231 \wedge x < 55.5014702134197$$
$$x > 60.7374579694027 \wedge x < 61.7846555205993$$
$$x > 63.8790506229925 \wedge x < 68.0678408277789$$
$$x > 70.162235930172 \wedge x < 74.3510261349584$$
$$x > 76.4454212373516 \wedge x < 77.4926187885482$$
$$x > 82.7286065445312 \wedge x < 83.7758040957278$$
$$x > 85.870199198121 \wedge x < 90.0589894029074$$
$$x > 92.1533845053006 \wedge x < 96.342174710087$$
$$x > 98.4365698124802 \wedge x < 99.4837673636768$$
$$x > 269.129770657526 \wedge x < 275.412955964705$$
$$x > 3803.42150594604$$
Solving inequality on a graph