Impossible Integration involving cosx/sqrt(a-bcosx)

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Discussion Overview

The discussion revolves around the integration of the function \(\int \frac{\cos x}{\sqrt{a - b \cos x}}dx\). Participants explore various techniques for solving this integral, including integration by parts, substitutions, and reference to integral tables.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant expresses difficulty in integrating the function despite trying multiple techniques, indicating a challenge in finding a solution.
  • Another participant suggests using Wolfram Alpha or integral tables as potential resources for finding the integral.
  • A third participant mentions that Mathematica provides a result consistent with integral tables, specifically referencing Gradshteyn and Ryzhik.
  • One participant reflects on the limitations of standard techniques for integrals, noting that many require defining new functions, and expresses a preference for looking up integrals in tables or using software for efficiency.
  • Another participant acknowledges the convenience of integral tables and software but emphasizes the impracticality of relying on them during exams, expressing a desire for a technique to solve the integral directly.

Areas of Agreement / Disagreement

Participants do not reach a consensus on a method to solve the integral directly. There are differing views on the reliance on computational tools versus traditional techniques.

Contextual Notes

Participants highlight the potential need for new functions in solving certain integrals, indicating that standard methods may not suffice. The discussion reflects a variety of approaches and the limitations of available techniques.

Who May Find This Useful

This discussion may be useful for students and practitioners in mathematics or physics who are interested in integration techniques and the challenges associated with specific integrals.

flux!
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Ok, I have encountered this one a few hours ago:
\int \frac{cos x}{\sqrt{a - b cos x}}dx
I have tried all techniques I know, integration by part, half-angle formula, substitution, trigo approach, and so on, but it seems, I could not integrate this one. I am no noob in integration, but this one is a bit difficult. How do I integrate it?
 
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Wolfram Alpha? Integral table?
 
I suspected that. After I learned that a lot of integrals cannot be solved without essentially defining a new function (like erf and the ellipticals), I got in the habit after spinning my wheels a bit with the standard techniques of looking them up in G&R to see if they were do-able.

When MMa came along, it was faster than looking in G&R. WA is even more convenient.
 
Yes of course, it is really convenient to look into table of integrals, but it is just impossible to do on exams. I hope we could have a technique to solve it.
 

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