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Homework Help: Trigonometry Proving the statement is innocent

  1. Jan 31, 2012 #1
    1. The problem statement, all variables and given/known data
    Prove this statement. (1+sinx)(1-sinx)=cos^2

    2. Relevant equations

    3. The attempt at a solution
    statement Reason
    (1+sinx)(1-sinx) Given
    1^2-sinx+sinx+sinx^2 GCF
    1+sinx^2 Cancel
    1+ (1/cscx) I'm stuck after that
  2. jcsd
  3. Jan 31, 2012 #2
    Look at your negatives again, you're missing one, which is practically the final step towards finding the solution.
  4. Jan 31, 2012 #3


    User Avatar
    Homework Helper

    You can simply use (a+b)(a-b) = a2 - b2, as it's considered a "commonly understood" identity.
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