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Homework Help: Verifying the Identity

  1. Apr 2, 2008 #1

    I'm new to this site and I'm very happy that I found it. My Pre-cal 2 teacher has been no help to me when it comes to explaining certain steps needed to solve a problem. Overall I'm having a hard time choosing the correct identity needed to solve the problems. However what I do not understand about this particular problem is how to change the denominator.

    The question is:

    Sec/Tan -Tan/Sec = cosxcotx

    I started by expanding sec and tan which gave me (1/cos)/(sin/cos)-(cos/sin)/(1/cos)

    but what should I do to change the denominator?
  2. jcsd
  3. Apr 2, 2008 #2

    Tom Mattson

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    Staff Emeritus
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    Gold Member

    That's a good start. Now think back to arithmetic: What do you do when you are asked to divide two fractions? I ask this, because that's exactly what you have there. For instance:


    Does that help?
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