Results 1 to 3 of 3

Math Help - Rearranging an equation using a simple trigonometric identity

  1. #1
    Newbie evanator's Avatar
    Joined
    Mar 2010
    From
    Ireland
    Posts
    24

    Rearranging an equation using a simple trigonometric identity

    Hi all,

    I have a mental block on a certain very simple trigonometry problem. I know I will slap my forehead when I see the solution. I therefore ask for your indulgence and thank, in advance, any responders. Here is the question and my attempt:

    Using \tan \theta \equiv \frac{\sin \theta}{\cos \theta}, show that the equation \tan \theta = \sin \theta can be written as \sin \theta (\cos \theta - 1) = 0 provided that \cos \theta \neq 0.

    Here is what I have done already:

    \tan \theta = \sin \theta

    \sin \theta = \frac{\sin \theta}{\cos \theta}

    \sin \theta = \sin \theta \cos \theta

    \cos \theta = 1

    I am not at all sure that I am on the right track. Any help would be sincerely appreciated.

    Regards,

    Evanator
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,693
    Thanks
    450
    Quote Originally Posted by evanator View Post
    Hi all,

    I have a mental block on a certain very simple trigonometry problem. I know I will slap my forehead when I see the solution. I therefore ask for your indulgence and thank, in advance, any responders. Here is the question and my attempt:

    Using \tan \theta \equiv \frac{\sin \theta}{\cos \theta}, show that the equation \tan \theta = \sin \theta can be written as \sin \theta (\cos \theta - 1) = 0 provided that \cos \theta \neq 0.

    Here is what I have done already:

    \tan \theta = \sin \theta

    \sin \theta = \frac{\sin \theta}{\cos \theta}

    \sin \theta = \sin \theta \cos \theta

    starting from the above step ...

    0 = \sin{t}\cos{t} - \sin{t}

    0 = \sin{t}(\cos{t} - 1)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie evanator's Avatar
    Joined
    Mar 2010
    From
    Ireland
    Posts
    24
    I was right. It was a doh! moment. Thank you very much, skeeter.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 9
    Last Post: March 23rd 2010, 08:42 PM
  2. Replies: 4
    Last Post: March 21st 2010, 09:29 PM
  3. Replies: 6
    Last Post: March 21st 2010, 08:17 PM
  4. Trigonometric Identity Equation
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: November 21st 2009, 02:43 AM
  5. simple trigonometric equation help
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 24th 2008, 02:28 PM

Search Tags


/mathhelpforum @mathhelpforum