Simplifying Trigonometric Expression and Solving Integral

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SUMMARY

The forum discussion focuses on simplifying the integral of the expression \(\int \frac{\sin^{2}(u) - \cos^{2}(u)}{\sqrt{\sin^{4}(u) + \cos^{4}(u)}} \, du\). Participants identified that the denominator can be expressed as \(\sqrt{\frac{2 - \sin^{2}(2u)}{2}}\) and the numerator simplifies to \(-\cos(2u)\). A substitution of \(t = \sin(2u)\) was suggested to facilitate the integration process. This approach streamlines the solution and highlights the importance of recognizing trigonometric identities in integral calculus.

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  • Understanding of integral calculus and trigonometric identities
  • Familiarity with substitution methods in integration
  • Knowledge of simplifying square root expressions involving trigonometric functions
  • Ability to manipulate and transform trigonometric expressions
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  • Study trigonometric identities, particularly \(\sin(2u)\) and \(\cos(2u)\)
  • Learn advanced techniques in integration, focusing on substitution methods
  • Explore the simplification of complex trigonometric expressions in calculus
  • Practice solving integrals involving square roots of trigonometric functions
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Students studying calculus, particularly those focusing on integral calculus and trigonometric functions, as well as educators seeking to enhance their teaching methods in these topics.

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Homework Statement


[tex]\int sin^{2} u - cos^{2} u / \sqrt{sin^{4} u + cos^{4} }[/tex]


Homework Equations


The Attempt at a Solution



[tex]\int sin^{2}(u) - cos^{2}(u) / \sqrt{sin^{4}(u) + cos^{4}(u)}[/tex]
then
[tex] \sqrt{sin^{4} u + cos^{4}} <br /> = \sqrt{(sin^{2}(u) + cos^{2}(u))^{2} - sin^{2}(u)cos^{2}(u)} <br /> = \sqrt{1 - 2sin^{2}(u)cos^{2}(u)}<br /> = \sqrt{\frac{1+cos^{2}(2u)}{2}} <br /> OR \sqrt{\frac{2 - 2sin^{2}(2u)}{2}}[/tex]that's as much as I could simplify.. any help would be appreciated, thanks
 
Last edited:
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Your numerator is pretty close to being cos(2u). Can you express the denominator in terms of sin(2u)? Then you should be able to see the substitution to use.
 
wow, the substitution has been right in front me! I've been blind..

so the denominator is [tex]\sqrt{\frac{2 - sin^{2}(2u)}{2}}[/tex]

and the numerator is -cos(2u)

so I can use t = sin(2u)

thanks!
 
Last edited:

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