Calculus 2: Trigonometric Substitution, using Z = tan(x/2)

In summary, the conversation is about solving a calculus problem involving substitution and using the tangent half-angle formula. The person asking for help is stuck and cannot find any information online about the substitution they are using. Another person suggests checking for mistakes in their derivation and changing the limits if necessary. The issue is eventually resolved and the person thanks the other for their help.
  • #1
kiz
4
0

Homework Statement



2e2jsc8.jpg

Homework Equations



25rlguf.jpg

The Attempt at a Solution



After substituting:

2cf7axc.jpg

Using
14wzxiw.jpg

2yo47qx.jpg

I'm stuck here:
dzlsp.jpg

I can't seem to find anything online about this substitution. Any help would be appreciated. thanks.
 
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  • #2
kiz said:

Homework Statement



2e2jsc8.jpg

Homework Equations



25rlguf.jpg

The Attempt at a Solution



After substituting:

2cf7axc.jpg

Using
14wzxiw.jpg

2yo47qx.jpg

I'm stuck here:
dzlsp.jpg

I can't seem to find anything online about this substitution. Any help would be appreciated. thanks.

I am so glad I have no need to remember any of this. my computer does all the calculations for me :)
 
  • #3
http://en.wikipedia.org/wiki/Tangent_half-angle_formula You seem to have turned a '2' into a 'z' in you dx derivation. And you would have to change the limits to 'z' limits instead of 'x' limits if you are going to stick with the variable z. Otherwise just find the indefinite integral in terms of z and change the function back to x.
 
  • #4
Dick said:
http://en.wikipedia.org/wiki/Tangent_half-angle_formula You seem to have turned a '2' into a 'z' in you dx derivation. And you would have to change the limits to 'z' limits instead of 'x' limits if you are going to stick with the variable z. Otherwise just find the indefinite integral in terms of z and change the function back to x.

Okay, thanks for the help, I'm looking at the solution and it has [tex]1[/tex] and [tex]\sqrt{3}[/tex] for the bounds, but I do not get that when insert [tex]\frac{\pi}{3}[/tex] and [tex]\frac{\pi}{2}[/tex].

EDIT:

I got it, guess I am blind. Thanks again.
 
Last edited:

1. What is trigonometric substitution in Calculus 2?

Trigonometric substitution is a technique used in calculus to simplify integrals involving trigonometric functions. It involves substituting a trigonometric expression in place of a variable in order to simplify the integral and make it easier to solve.

2. How is trigonometric substitution used in Calculus 2?

Trigonometric substitution is used in Calculus 2 to solve integrals that involve expressions with trigonometric functions, specifically when dealing with square roots or rational powers. The substitution allows for the integral to be transformed into a simpler form, making it easier to solve.

3. What is the formula for using Z = tan(x/2) in trigonometric substitution?

The formula for using Z = tan(x/2) in trigonometric substitution is:

tan(x/2) = Z, which can be rewritten as x = 2arctan(Z) or x = 2tan-1(Z).

4. How do you know when to use Z = tan(x/2) in trigonometric substitution?

You should use Z = tan(x/2) in trigonometric substitution when the integral involves a square root of a quadratic expression, or when the integrand contains a rational function with a quadratic denominator. Additionally, you can also use this substitution when dealing with integrals that involve the trigonometric functions secant and tangent.

5. What are the advantages of using Z = tan(x/2) in trigonometric substitution?

Using Z = tan(x/2) in trigonometric substitution has several advantages. It can simplify the integral, turning it into a more manageable form. Additionally, it can help solve integrals that would be difficult to solve using other methods. It also allows for the use of trigonometric identities to further simplify the integral. Finally, it can be used to solve a wide range of integrals involving trigonometric functions.

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