Integrating Trigonometric Functions: A Helpful Guide

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Homework Help Overview

The discussion revolves around integrating trigonometric functions, specifically the integrals of expressions involving cosine and sine. Participants are exploring methods to solve the integrals ∫(1/(1+cos(x)))dx and ∫(x+sin(x))/(1+cos(x))dx.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Participants discuss using integration by parts and substitution methods. There are hints suggesting the use of trigonometric identities, particularly involving cos(x). Some participants express uncertainty about their results and seek validation of their approaches.

Discussion Status

Several participants have shared their attempts and results, with some providing hints and corrections. There is an ongoing exploration of different methods and identities, but no explicit consensus has been reached regarding the final solutions.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the information they can share or the methods they can use. There is a noted emphasis on the importance of including arbitrary constants in their final answers.

Redoctober
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Homework Statement


Determine the integral of the following

∫(1/(1+cos(x)).dx
∫(x+sin(x))/(1+cos(x)).dx

The Attempt at a Solution



I tried integration by parts and substution , but didn't work !
Help :/ !
 
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Show us what you've got. Here are hints:
1 - Use the identity that cos(x)=2*cos(x/2)-1, and then use a simple substitution.
2 - Somewhat similar to the first one.
 
DivisionByZro said:
Show us what you've got. Here are hints:
1 - Use the identity that cos(x)=2*cos(x/2)-1, and then use a simple substitution.
2 - Somewhat similar to the first one.

I got tan(x/2) + C for the first But nothin for the second .
i did as follows

∫(x+sin(x))/(x+cos(x)).dx

simplified it to

∫(x*sec^2(x)).dx + 2∫tan(x/2).dx

I then i integrated them , i used integration by parts for then right hand integral
Then i finally got
2x*tan(x/2)

Is it correct :D ?
 
DivisionByZro said:
Show us what you've got. Here are hints:
1 - Use the identity that cos(x)=2*cos(x/2)-1, and then use a simple substitution.
2 - Somewhat similar to the first one.
That identity should be
cos(x)=2*cos2(x/2)-1 .​
 
Redoctober said:
I got tan(x/2) + C for the first But nothin for the second .
i did as follows

∫(x+sin(x))/(x+cos(x)).dx

simplified it to

∫(x*sec^2(x)).dx + 2∫tan(x/2).dx

I then i integrated them , i used integration by parts for then right hand integral
Then i finally got
2x*tan(x/2)

Is it correct :D ?
The ∫(x*sec^2(x)).dx + 2∫tan(x/2).dx that you have should be: ∫(x*sec^2(x/2)).dx + 2∫tan(x/2).dx .

Yes, your answer is correct, if you add an arbitrary constant.
 
SammyS said:
The ∫(x*sec^2(x)).dx + 2∫tan(x/2).dx that you have should be: ∫(x*sec^2(x/2)).dx + 2∫tan(x/2).dx .

Yes, your answer is correct, if you add an arbitrary constant.

Oh ok thanks :D ! i always forget the arbitrary unit lol xD
 

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