Double Angle Identity Mystery: Solving 2/(tanx+cotx)=sinx

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SUMMARY

The equation 2/(tanx + cotx) = sinx has been analyzed, revealing that the left-hand side simplifies to sin(2x) rather than sinx. The simplification process involves using double angle identities and Pythagorean identities, leading to the conclusion that the textbook's assertion of the answer being sinx is incorrect. Participants in the discussion confirm the validity of the derived result, indicating a potential error in the textbook.

PREREQUISITES
  • Understanding of trigonometric identities, specifically double angle identities.
  • Familiarity with the tangent and cotangent functions.
  • Knowledge of Pythagorean identities in trigonometry.
  • Ability to manipulate algebraic expressions involving trigonometric functions.
NEXT STEPS
  • Study the derivation and applications of double angle identities in trigonometry.
  • Learn how to simplify expressions involving tangent and cotangent functions.
  • Explore common errors in trigonometric textbooks and how to identify them.
  • Practice solving similar trigonometric equations to reinforce understanding.
USEFUL FOR

Students studying trigonometry, educators teaching trigonometric identities, and anyone seeking to clarify common misconceptions in trigonometric equations.

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

thanks guys
 

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