- #1
hanelliot
- 18
- 0
Homework Statement
[itex]\int dx/(cosx + cos3x)[/itex]
Homework Equations
The Attempt at a Solution
Not sure if I'm doing this right.
[itex]1/cosx + cos3x = 1/2cosx * cos2x = cosx/cosx * 2cosxcos2x = cosx/2cos^2xcosx = (1/2)*(cosx)/[(1-sin^2x)(1-2sin^2x)][/itex]
then we let t = sinx and get [itex]\int dx/(cosx + cos3x) = 1/2 [1/(1-t^2)(1-2t^2)]dt[/itex]
Any comments please..