Addition and Subtraction Formulas

Proposition (Addition and Subtraction Formulas) The following formulas hold for all angles and where the functions are defined.  

Example (Addition and Subtraction Formulas) Find the exact value of

    Solution. Writing we have,
    












Example (Addition and Subtraction Formulas)  Find the exact value of and given and is in quadrant 4.

    Solution. Since and is in quadrant 4, we have Therefore,











Example (Addition and Subtraction Formulas)  Prove the trigonometric identity:

    Solution. We have










    


Example (Addition and Subtraction Formulas)  Solve the equation

    Solution. We have
    












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Addition And Subtraction Formulas
Published by Library of Math -- Online math organized by subject into topics.
Written by Smith, David A.
http://www.libraryofmath.com/addition-and-subtraction-formulas.html