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Trig Identity

  • Thread starter nzashadow
  • Start date
  • #1
10
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Homework Statement



2/(tanx+cotx)=sinx

Homework Equations



Double Angle Identities, Pythagorean Identities

The Attempt at a Solution



2/(tanx+cotx)=

2/[(sinx/cosx)+(cosx/sinx)]=

2/[((sinx)^2+(cosx)^2)/(sinxcosx)]=

2sinxcosx/[(sinx)^2+(cosx)^2]=

2sinxcosx = sin(2x) =/= sinx

The book I'm getting this problem in says the answer is sinx, however I get sin(2x) which does not equal sinx. I am certain I am right, though I may also be making a stupid mistake :P
 

Answers and Replies

  • #2
L2E
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Your answer seems correct went over it a couple of times, It seems like an error with your textbook.
 
  • #3
Delta2
Homework Helper
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Seems correct to me too, maybe the textbook has tan(x/2)+cot(x/2) instead?
 
  • #4
you are right
 
  • #5
10
0
nah it says tanx+cotx, went over it many times.

thanks guys
 

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