Identities simplify expression

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SUMMARY

The discussion centers around simplifying the expression sin3xcosx - cos3xsinx using the sine addition formula, specifically sin(a-b) = sin(a)cos(b) - cos(a)sin(b). The correct simplification leads to the result sin(3x - x), which equals sin(2x). This method effectively demonstrates how to apply trigonometric identities to simplify complex expressions.

PREREQUISITES
  • Understanding of trigonometric identities
  • Familiarity with the sine addition formula
  • Basic knowledge of angle manipulation in trigonometry
  • Ability to recognize and apply sine and cosine functions
NEXT STEPS
  • Study the derivation and applications of the sine addition formula
  • Explore other trigonometric identities such as the cosine addition formula
  • Practice simplifying complex trigonometric expressions
  • Learn about angle transformations and their implications in trigonometry
USEFUL FOR

Students studying trigonometry, educators teaching trigonometric identities, and anyone looking to enhance their skills in simplifying trigonometric expressions.

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I have been trying to do this problem for a long time, and still can not do it. I know the answer is sin2x, but I have no idea how to do it:

write expression as sine, cosine, or tangent of an angle

sin3xcosx - cos3xsinx

THANKS!
 
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Use the sine addition formula, sin(a-b)=sin(a)cos(b)-cos(a)sin(b). Line that up with your expression and figure out what a and b should be.
 

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