Results 1 to 4 of 4

Math Help - How to turn 9 sin120 into (9*(squareroot3))/2

  1. #1
    Junior Member
    Joined
    Jan 2011
    Posts
    34

    How to turn 9 sin120 into (9*(squareroot3))/2

    Hello

    How would I go about converting 9 sin120 into the form with a surd:
    9*(squareroot of 3)
    -------------------
    ............2
    ?
    Thank you
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,490
    Thanks
    1391
    You should know that \displaystyle \sin{\left(180^{\circ} - \theta^{\circ}\right)} \equiv \sin{\theta^{\circ}} for \displaystyle 0^{\circ} < \theta^{\circ} < 90^{\circ}.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    11,621
    Thanks
    426
    Quote Originally Posted by anees7112 View Post
    Hello

    How would I go about converting 9 sin120 into the form with a surd:
    9*(squareroot of 3)
    -------------------
    ............2
    ?
    Thank you
    value from the unit circle ...

    \sin(120^\circ) = \dfrac{\sqrt{3}}{2}

    Follow Math Help Forum on Facebook and Google+

  4. #4
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Although the other two methods are easier you can use the fact that \sin(A+B) = \sin A \cos B + \cos A \sin B \text{  where  } A = 90^{\circ} \text{ and } B = 30^{\circ}

    30 and 90 are, of course, found on a 30-60-90 triangle
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: October 9th 2011, 12:18 PM
  2. can you help turn this into a math formula?
    Posted in the Discrete Math Forum
    Replies: 1
    Last Post: April 4th 2010, 02:59 AM
  3. How to turn a decimal into a fration
    Posted in the Algebra Forum
    Replies: 1
    Last Post: October 8th 2008, 03:27 PM
  4. Replies: 4
    Last Post: September 15th 2008, 11:47 PM
  5. how to turn this into echelon matrix?
    Posted in the Advanced Algebra Forum
    Replies: 1
    Last Post: August 3rd 2008, 01:24 PM

Search Tags


/mathhelpforum @mathhelpforum