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-   -   Proofing Pre Calculus Identities (https://www.askmehelpdesk.com/showthread.php?t=399578)

  • Sep 24, 2009, 03:30 PM
    aggy113
    precalculus identities
    prove the following identities?
    a.) (1 - cosX)(cscX + cotX)=sinX
  • Sep 25, 2009, 03:04 AM
    ArcSine
    Here's one way your proof could proceed: Working on the left-hand side, multiply it out:



    Re-express the terms (I'll let you fill in the steps in your proof):



    Note that two of the terms cancel out, and the remaining two terms, having a common denominator, can be written



    Now look at the numerator, and think of the Pythagorean Identity. Can you finish it up from here?

    Also keep in mind that with many trig IDs there are multiple possible paths to the same conclusion. Good luck!
  • Jan 12, 2010, 06:10 PM
    TANDE005
    How do I solve the following identity?

    secxcscx=tanx + cotx
  • Jan 12, 2010, 07:38 PM
    galactus


    Please start your own thread.

    But here goes:


    Start with the right side and turn it into the left side.



    Cross multiply:



    Notice the famous identity in the numerator is equal to 1.




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