Integral of cos^3 theta

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  • #1
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Would very much appreciate a hint on how to start this off.
So far I have cos theta = (1-t^2)/(1+t^2). After squaring this and doing various substitutions, I get (cos theta)^3, which can't be right.
 

Answers and Replies

  • #2
Tide
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I'm not sure what you're asking but if you want the integral indicated in the title of your post this may help:

[tex]\cos^3 \theta = \cos^2 \theta \cos \theta = \left(1-\sin^2 \theta \right) \frac {d \sin \theta}{d\theta}[/tex]
 
  • #3
53
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Many thanks. I'll give it a shot.
 
  • #4
53
0
I got cos theta - (1/3)cos^3 theta + C
Does this look right?
 
  • #5
Fredrik
Staff Emeritus
Science Advisor
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Almost. It should be sin, not cos.
 

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