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Proving Identities

  1. Feb 5, 2009 #1
    1. The problem statement, all variables and given/known data

    Prove the following identities.

    a) cosx/1-sinx = secx + tanx

    b) cos^2x+ sinxcosx/tanx = 2cos^2x


    3. The attempt at a solution

    Well what I tried doing was substituting the appropriate compound angle formulas, double angle formulas, quotient identities, and reciprocal identities, but I just can't seem to solve it all the way (if thats what "prove" means in the first place anyways)

    Anyone have any idea how I'd go about solving them? This is what I have so far.

    a) cosx/1-sinx = 1/cosx + sinx/cosx

    b) I haven't started yet :/
     
  2. jcsd
  3. Feb 5, 2009 #2
    to prove part a) you should start with one side of the equation and manipulate it to arrive at the other side of the equation.

    I'd begin with the left hand side. To get started, divide numerator and denominator by a certain term (do you see which term?)
     
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