Integrating Trigonometric Functions: A Helpful Guide

  • Thread starter Redoctober
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In summary, the conversation discusses two integrals: ∫(1/(1+cos(x)).dx and ∫(x+sin(x))/(1+cos(x)).dx. The suggested approach is to use the identity cos(x)=2*cos(x/2)-1 and a simple substitution. The final answer for the second integral is 2x*tan(x/2) + C, with the reminder to include an arbitrary constant.
  • #1
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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  • #2
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.
 
  • #3
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 ?
 
  • #4
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 .​
 
  • #5
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.
 
  • #6
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
 

FAQ: Integrating Trigonometric Functions: A Helpful Guide

What is integration and why is it important?

Integration is a mathematical process of finding the total or sum of a quantity by adding up infinitely small pieces. It is important because it allows us to solve problems involving continuous change, such as finding areas, volumes, and displacement.

What are the different methods of integration?

The most commonly used methods of integration are the following: integration by substitution, integration by parts, partial fractions, and trigonometric substitution. These methods allow us to solve a variety of integration problems by using different techniques.

How do I know which method of integration to use?

The choice of method depends on the form of the integrand (the function being integrated). Generally, we try to manipulate the integrand to make it easier to integrate using one of the methods mentioned above. This requires practice and familiarity with the different techniques.

Can integration be used to find the area under a curve?

Yes, integration can be used to find the area under a curve. This is known as the definite integral, where we specify the limits of integration (the start and end points) to find the exact area between the curve and the x-axis.

How can I check if my integration answer is correct?

You can check your answer by taking the derivative of the integrated function. If the derivative matches the original function, then your answer is correct. You can also use online integration calculators to verify your answer or solve the problem step-by-step.

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