Integration with Sines and Cosines

  • Thread starter Thread starter Ayesh
  • Start date Start date
  • Tags Tags
    Integration
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!
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

Similar threads

Replies
15
Views
2K
Replies
3
Views
506
Replies
4
Views
1K
Replies
7
Views
2K
Replies
6
Views
2K
Replies
20
Views
2K
Replies
5
Views
2K
Back
Top