Can the set of x be found for -1 ≤ 1/(1+cosx) ≤ 1?

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SUMMARY

The discussion focuses on solving the inequality -1 ≤ 1/(1 + cos(x)) ≤ 1. Participants clarify that cos(x) cannot equal -1, leading to the conclusion that 1/(1 + cos(x)) is constrained between 0.5 and infinity. The key insight is that since 1/(1 + cos(x)) is positive, its reciprocal must be either greater than 1 or less than -1, guiding the solution process. Understanding trigonometric identities is essential for further progress.

PREREQUISITES
  • Trigonometric identities, specifically involving cosine functions
  • Understanding of inequalities and their properties
  • Knowledge of reciprocal functions and their behavior
  • Basic algebraic manipulation skills
NEXT STEPS
  • Study trigonometric identities related to cosine, particularly 1 + cos(x)
  • Learn about solving inequalities involving rational functions
  • Explore the properties of reciprocal functions and their implications
  • Practice solving similar inequalities to reinforce understanding
USEFUL FOR

Students studying trigonometry, educators teaching mathematical inequalities, and anyone looking to enhance their problem-solving skills in algebra and trigonometric functions.

IsrTor
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Homework Statement


solve the inequality:
-1[tex]\leq[/tex] 1[tex]/[/tex](1+cosx) [tex]\leq[/tex]1

The Attempt at a Solution



firstly cosx does not equal -1 but you'll see doesn't help much
-1<cosx<1
0<cosx+1<2
that makes the above equation 1/(1+cosx) between 0.5 and infinity. but I have no clue as to how to find the set of x which solve the inequality
 
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IsrTor said:
solve the inequality:
-1[tex]\leq[/tex] 1[tex]/[/tex](1+cosx) [tex]\leq[/tex]1

Hi IsrTor! :smile:

You need to learn your trigonometric identities …

what does 1 + cosx also equal? :wink:
 
IsrTor said:

Homework Statement


solve the inequality:
-1[tex]\leq[/tex] 1[tex]/[/tex](1+cosx) [tex]\leq[/tex]1

The Attempt at a Solution



firstly cosx does not equal -1 but you'll see doesn't help much
-1<cosx<1
0<cosx+1<2
that makes the above equation 1/(1+cosx) between 0.5 and infinity. but I have no clue as to how to find the set of x which solve the inequality

Since 1/(1 + cosx) is between -1 and 1, its reciprocal has to be larger than 1 or smaller than -1, depending on whether 1/(1 + cos x) is positive or negative, respectively.

Can you do something with that?
 

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