19.2 Sum and difference identities

Sum and difference identities

Trig identities are formulas developed based on Pythagorean Theorem. These identities show us how and where to find the sine, cosine, and tangent of the sum and difference of two given angles.


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sin(A+B) \sin (A + B)
sin(AB) \sin (A - B)
cos(A+B) \cos (A + B)
cos(AB) \cos (A - B)
tan(A+B) \tan (A + B)
tan(AB) \tan (A - B)
  • 1.
    Simplify expressions

  • 2.
    Prove Identities
  • 3.
    Without using a calculator, evaluate:
Teacher pug

Sum and difference identities

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