Results 1 to 4 of 4

Math Help - Finding the equation for the normal

  1. #1
    Member
    Joined
    Nov 2012
    From
    Singapore
    Posts
    180

    Finding the equation for the normal

    Find the equation of the normal to y = cosec(2x) at the point where x = pi/4.

    Differentiating cosec(2x) = -2cot(2x)cosec(2x)
    At x = pi/4, dy/dx = -2cot(pi/2)cosec(pi/2)

    I am unable to get a value for the dy/dx of the tangent since cot(pi/2) is undefined! How should I continue or did I make any mistakes?

    Thank you very much!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor MarkFL's Avatar
    Joined
    Dec 2011
    From
    St. Augustine, FL.
    Posts
    1,988
    Thanks
    734

    Re: Finding the equation for the normal

    The cotangent function is not undefined there. Look at it again.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,831
    Thanks
    1602

    Re: Finding the equation for the normal

    Quote Originally Posted by Tutu View Post
    Find the equation of the normal to y = cosec(2x) at the point where x = pi/4.

    Differentiating cosec(2x) = -2cot(2x)cosec(2x)
    At x = pi/4, dy/dx = -2cot(pi/2)cosec(pi/2)

    I am unable to get a value for the dy/dx of the tangent since cot(pi/2) is undefined! How should I continue or did I make any mistakes?

    Thank you very much!
    Surely if \displaystyle \begin{align*} \cot{\left( \frac{\pi}{2} \right)} \end{align*} is undefined, then the tangent line is vertical. So wouldn't the normal line have to be horizontal?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Member
    Joined
    Nov 2012
    From
    Singapore
    Posts
    180

    Re: Finding the equation for the normal

    Hi thanks! But aren't co tangents undefined? I cannot find q value, it keeps coming back undefined..unless I type the whole cot and cosec in?
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding Tangent Line and Normal of a parametric equation
    Posted in the Differential Geometry Forum
    Replies: 2
    Last Post: January 14th 2012, 08:02 AM
  2. Replies: 6
    Last Post: July 23rd 2010, 01:36 PM
  3. [SOLVED] Finding equation of normal to a curve.
    Posted in the Calculus Forum
    Replies: 8
    Last Post: July 18th 2010, 02:56 AM
  4. Finding the equation of tangent and normal
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 5th 2009, 07:22 AM
  5. finding the equation of the normal
    Posted in the Algebra Forum
    Replies: 1
    Last Post: October 26th 2008, 10:59 AM

Search Tags


/mathhelpforum @mathhelpforum