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Homework Help: Fundamental Trig Identities

  1. Mar 25, 2008 #1
    I just don't get this stuff. I've been trying on my own with the book. Also, is there a better way to post this?

    1. The problem statement, all variables and given/known data
    tanx 1 + secx
    _________ + _________ = 2csc x
    1 + secx tanx
    I need to prove that this side equals the other.

    2. Relevant equations

    http://users.rcn.com/mwhitney.massed/trigresources/trig-reference.html [Broken]
    ^^The reference I was using.

    3. The attempt at a solution
    tanx(tanx) 1 + secx(1 + secx)
    _________ + _________ = 2csc x
    1 + secx(tanx) tanx(1 + secx)



    tan2 x 1 + 2secx + sec2x
    ________________ + _________________
    1 + secx(tanx) (tanx)1 + secx



    tan2x + 1 + 2secx + sec2x
    _________________________
    1 + cos 1/x(tanx)


    sec2x + 2cos 1/x + sec2x
    _________________________
    1 + cos 1/x(tanx)

    This is as far as I get before I get lost.
     
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Mar 25, 2008 #2

    Integral

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    Staff Emeritus
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    Gold Member

    First look at https://www.physicsforums.com/showthread.php?t=8997"thread to learn how to use LaTex. With that you can do this:

    [tex] \frac { \tan x } { 1 + \sec x} + \frac {1 + \sec x} {\tan x} = 2 \csc x [/tex]

    Now, try multipling the top and bottom of the first term on the left by [tex] 1 - \sec x [/tex]

    BTW: Just click on my equations to see what I typed to produce them.
     
    Last edited by a moderator: Apr 23, 2017
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