Results 1 to 8 of 8

Math Help - Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

  1. #1
    Newbie
    Joined
    Mar 2013
    From
    United States
    Posts
    3

    Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    Hey everybody,

    I've been stuck as to how to simplify this: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]y

    Apparently it simplifies to sinx, but i have no idea how they got there. Been working on this for about a half an hour now and i keep getting stuck, help?

    Thanks!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member
    Joined
    Nov 2011
    From
    Crna Gora
    Posts
    420
    Thanks
    64

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    \cot x=\frac{\cos x}{\sin x}

    \sec x=\frac{1}{\cos x}

    \tan x=\frac{\sin x}{\cos x}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Mar 2013
    From
    United States
    Posts
    3

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    Quote Originally Posted by princeps View Post
    \cot x=\frac{\cos x}{\sin x}

    \sec x=\frac{1}{\cos x}

    \tan x=\frac{\sin x}{\cos x}
    So convert everything to sin and cosine then?

    [(cosxcotx)/(secx+tanx)] + (sinx)/(secx-tanx)]
    to sin and cosine
    [(cos2x/sinx)/(1/cosx+sinx/cosx)+(1/cosx-sinx/cosx)]
    group together common denominators
    [(cos2x/sinx)/(1+sinx/cosx)+(1-sinx/cosx)]
    what now?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,113
    Thanks
    325

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    If you mean this:

     \frac {cos x \ cot x}{sec x+ tan x} + \frac {sin x}{sec x - tan x}

    then no - it does not simpify to \sin x.

    There is an extra close bracket symbol ']' in your original post, and an extraneous 'y' charcter after it in the body of the post, so perhaps I am not interpreting your formula correctly.
    Last edited by ebaines; March 12th 2013 at 12:05 PM.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Feb 2013
    From
    Oakland, CA
    Posts
    12

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    Yeah, I wrestled with this one and couldn't make it reduce to sin(x). Just to confirm, I fed it through Mathematica and Mathematica waived a little white flag over it too. So either you copied it wrong or there's a misprint in your book.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,113
    Thanks
    325

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    I've learned when trying to help people with trig identities - if I can't work it out in 2 minutes or less then I put it in excel and see if it works for a value like x = 0.1. It saves a lot of wasted time...
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Feb 2013
    From
    Oakland, CA
    Posts
    12

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    It's a good lesson for me. I have to learn to let go of a problem before my brain starts hurting...
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Newbie
    Joined
    Mar 2013
    From
    United States
    Posts
    3

    Re: Need Help Simplifying: [(cosxcotx)/(secx+tanx)] + (sinx)/(sex-tanx)]

    Quote Originally Posted by ebaines View Post
    If you mean this:

     \frac {cos x \ cot x}{sec x+ tan x} + \frac {sin x}{sec x - tan x}

    then no - it does not simpify to \sin x.
    Yeah... must've been an error in the textbook. thanks for the help anyways. I appreciate it
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 5
    Last Post: November 13th 2012, 04:06 PM
  2. Replies: 1
    Last Post: November 13th 2012, 03:24 PM
  3. Prove:(tanx/(1+tanx)) = (sinx/(sinx+cosx))
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: February 2nd 2011, 08:46 PM
  4. Integrating (sinx + secx)/tanx dx
    Posted in the Calculus Forum
    Replies: 7
    Last Post: March 4th 2008, 08:30 AM

Search Tags


/mathhelpforum @mathhelpforum