Results 1 to 4 of 4

Math Help - Solving trigonometric equations?

  1. #1
    Senior Member
    Joined
    Dec 2010
    From
    CPT
    Posts
    302

    Solving trigonometric equations?

    Can anyone help me solve these two problems

    sin2x-1=0
    2sinx cox-1=0 Then I am not sure how to proceed

    sinxtanx-sinx=0

    sinx (sinx/cosx)- sinx

    Sinx^2/ cosx -sinxcosx/cosx I am not sure if I am doing this right?
    Follow Math Help Forum on Facebook and Google+

  2. #2
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    It's easier not to expand.

    Add 1 to both sides: \sin(2x) = 1

    Take the arcsin of both sides: 2x = \dfrac{\pi}{2}

    x = \dfrac{\pi}{4} + k\pi \ \ ,\  k \in \mathbb{Z}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Dec 2010
    From
    CPT
    Posts
    302
    Thanks for your help however the second function I am still having problem solving.

    I narrowed it down to
    sinx^2-sinx=0 factor sin
    sinx(sinx-1)=0

    sinx=0 sinx=1
    x=0, 90,180,270,360 degrees?
    Last edited by homeylova223; March 1st 2011 at 05:21 PM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,855
    Thanks
    321
    Awards
    1
    Quote Originally Posted by homeylova223 View Post
    How would you take the arcsin in the equation I am not sure how to do it?
    Arcsine (or asn or sin^{-1} ) is the inverse of the sine function. So if we know that y = sin(x) then \sin^{-1}(y) = x. (The angle x is written in the form -\pi \leq x \leq \pi )

    Thus
    sin^{-1}(sin(2x)) = 2x

    and
    sin^{-1}(1) = \frac{\pi}{2} because sin \left ( \frac{\pi}{2} \right ) = 1.

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Solving trigonometric equations
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: April 22nd 2009, 12:52 PM
  2. Solving Trigonometric equations
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: March 30th 2009, 02:44 AM
  3. Solving Trigonometric equations
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: March 23rd 2009, 10:48 AM
  4. solving trigonometric equations
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: March 15th 2009, 03:03 PM
  5. Solving Trigonometric Equations
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 4th 2008, 09:47 PM

Search Tags


/mathhelpforum @mathhelpforum