What trig. identity is used here?

  • Thread starter Peon666
  • Start date
  • #1
108
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4/t [cos(wt/2)-1] = -8/t sin(wt/4)

?
 

Answers and Replies

  • #3
607
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double-angle formula, [itex]\cos(2\theta) = 1-2 \sin^2(\theta)[/itex] so [itex]\cos(2\theta)-1 = -2 \sin^2(\theta)[/itex] ... so your original formula is correct except for a missing square.
 
  • #4
108
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Thanks a lot. :)
 

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