Solving Inequality: (1+tg(x))*cos^2(x) > 1

  • Thread starter Thread starter Icelove
  • Start date Start date
  • Tags Tags
    Inequality
Click For Summary
SUMMARY

The inequality (1 + tg(x)) * cos^2(x) > 1 can be solved by transforming it into the form sin(x)cos(x) > sin^2(x). The key steps involve using the identity tg(x) = sin(x)/cos(x) and the double angle identity sin(2x) = 2sin(x)cos(x). The final rearrangement simplifies the problem, making it easier to solve without needing the quadratic formula.

PREREQUISITES
  • Understanding of trigonometric functions, specifically tangent and cosine.
  • Familiarity with trigonometric identities, including double angle identities.
  • Ability to manipulate inequalities involving trigonometric expressions.
  • Knowledge of basic algebraic rearrangement techniques.
NEXT STEPS
  • Study the derivation and application of trigonometric identities, particularly double angle identities.
  • Learn how to solve trigonometric inequalities effectively.
  • Explore the implications of rearranging trigonometric expressions in inequalities.
  • Practice solving similar inequalities involving trigonometric functions.
USEFUL FOR

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

Icelove
Messages
16
Reaction score
0

Homework Statement


(1 + tg(x)) * cos^2(x) > 1, solve the inequality


Homework Equations


tg(x) = sin(x)/cos(x)
cos(x) * sin(x) = 1/2 sin(2x)



The Attempt at a Solution


I got my final value of:
1-sin^2(x) + 1/2 sin(2x) > 1
but because of the 2 inside the sin
I'm kinda lost so I can't use quadratic formula I presume
 
Physics news on Phys.org
Let me rearrange that a little for you:

1/2sin(2x)>sin^2(x)

which is actually nicer in the following form:

sin(x)cos(x)>sin^2(x).

This should be easier to solve.
 
grief said:
Let me rearrange that a little for you:

1/2sin(2x)>sin^2(x)

which is actually nicer in the following form:

sin(x)cos(x)>sin^2(x).

This should be easier to solve.

It is important for you to realize where this came from.
If you have notes, cheat sheet, book, or webpage with trig identities, look at the double angle identities.
sin2x=2sinxcosx
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
Replies
5
Views
2K
Replies
8
Views
4K
Replies
3
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K