Integration with Sines and Cosines

  • Thread starter Thread starter Ayesh
  • Start date Start date
  • Tags Tags
    Integration
Click For Summary
SUMMARY

The discussion focuses on the integration of the function \(\int \frac{\sin x \cos x}{\sin^4 x + \cos^4 x} \, dx\). Participants utilize trigonometric identities such as \(\sin^2 x = \frac{1}{2} - \frac{1}{2} \cos(2x)\) and \(\cos^2 x = \frac{1}{2} + \frac{1}{2} \cos(2x)\) to simplify the integral. The solution approach involves rewriting the integral as \(\int \frac{1/2 \sin(2x)}{(1/2 - 1/2 \cos(2x))^2 + (1/2 + 1/2 \cos(2x))^2} \, dx\). The discussion confirms that this method is valid and suggests that recognizing the denominator as nearly the square of \(\cos^2 x + \sin^2 x\) could expedite the integration process.

PREREQUISITES
  • Understanding of trigonometric identities, specifically \(\sin^2 x\) and \(\cos^2 x\)
  • Familiarity with integral calculus and integration techniques
  • Knowledge of the double angle formula for sine, \(\sin(2x)\)
  • Experience with simplifying complex fractions in calculus
NEXT STEPS
  • Study the properties of trigonometric integrals, particularly those involving products of sine and cosine
  • Learn advanced techniques in integration, such as substitution and partial fractions
  • Explore the application of trigonometric identities in simplifying integrals
  • Practice integrating functions with complex denominators using trigonometric identities
USEFUL FOR

Students studying calculus, particularly those focusing on integration techniques, as well as educators seeking to enhance their teaching of trigonometric integrals.

Ayesh
Messages
29
Reaction score
0

Homework Statement



\intsinxcosx/sin^4x+cos^4x


Homework Equations



sin^2x=1/2-1/2cos(2x)

cos^2x=1/2+1/2cos(2x)

sinxcosx=1/2sin(2x)

The Attempt at a Solution



\int1/2 sin(2x)/(1/2-1/2cos(2x))^2 + (1/2 + 1/2cos(2x))^2

\int1/2 sin(2x)/1/2 + 1/2cos^2(2x)

...?

Am I on the right track?
 
Physics news on Phys.org
Hi Ayesh! :smile:

(have an integral: ∫ and try using the X2 tag just above the Reply box :wink:)

Ayesh said:
… \int1/2 sin(2x)/1/2 + 1/2cos^2(2x)

...?

Am I on the right track?

Yes, that's fine.

(though it would have been quicker to notice that the original denominator is almost the square of cos2x + sin2x :wink:)

And you should be able to integrate it immediately. :smile:
 
Thank you!
 

Similar threads

  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 20 ·
Replies
20
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K