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    jynx3943's Avatar
    jynx3943 Posts: 29, Reputation: 3
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    #1

    Nov 21, 2008, 01:39 PM
    Varifying Trig Identities
    I have a problem that I have worked on for a long time and cannot solve. It is really bugging me. The directions are to show the steps in varifying these identities...

    (cosx +sinx)/(cosx - sinx) - (cosx - sinx)/(cosx + sinx) =2tan(2x)

    I keep getting sooo close but just can't seem to arrive at 2tan(2x)! AHHHHH!! Please help as I am in need for a brain rest. Thank you kindly.
    galactus's Avatar
    galactus Posts: 2,271, Reputation: 282
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    #2

    Nov 21, 2008, 01:54 PM
    Did you just cross multiply and get:

    ?

    If so, this is equal to 2tan(2x).

    Because 4cos(x)sin(x)=2sin(2x)

    Also,

    Then, we get:
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