Solving the Integral of sin(1-x)sinx

  • Thread starter Thread starter powerplayer
  • Start date Start date
  • Tags Tags
    Integral
Click For Summary

Homework Help Overview

The discussion revolves around solving the integral of sin(1-x)sinx with participants exploring various methods of integration, particularly integration by parts and trigonometric identities.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants discuss using integration by parts and the potential oversight in handling negative signs during the integration process. There is also mention of exploring trigonometric identities, specifically the use of a double angle formula and the sine of a sum.

Discussion Status

The conversation includes attempts to clarify integration techniques and identify mistakes in the original poster's approach. Some participants suggest alternative methods, while others express confusion about applying trigonometric identities correctly. There is a sense of progress as one participant indicates they have resolved their confusion.

Contextual Notes

Participants are working within the constraints of homework rules, which may limit the types of guidance they can provide. There is an ongoing exploration of assumptions related to the integral's setup and the application of trigonometric identities.

powerplayer
Messages
25
Reaction score
0

Homework Statement



integral of sin(1-x)sinx dx

Homework Equations





The Attempt at a Solution



so i did by parts once and got -sinxcos(1-x) - integral of -cos(1-x)cosx dx

then i did by parts again and got -sinxcos(1-x) + cosxsin(1-x) - integral of -sin(1-x)sinx dx

if you take out the negative on the last integral you end up where you started? anyone know where i messed up?
 
Physics news on Phys.org
Instead of parts, you could try using a double angle formula on sin(1-x).
 
oh i think i see it i forgot to divide by the -1 each time i took the integral in the by parts
 
nevermind i still did not get the right answer how do i use double angle on sin(1-x_ i thought it had to be in the form sin2x?
 
Not quite the double angle formula, but rather the trig identity for sin of a sum.
 
i got it now thx
 

Similar threads

Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 15 ·
Replies
15
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K