Results 1 to 4 of 4

Math Help - find trigo ratio

  1. #1
    Member
    Joined
    Sep 2007
    Posts
    176

    find trigo ratio

    find trigo ratio
    Attached Thumbnails Attached Thumbnails find trigo ratio-out0064.jpeg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    Since \frac{\sqrt{3}+1}{2\sqrt{2}}=\frac{1}{2}\cdot\frac  {\sqrt{2}}{2}+\frac{\sqrt{3}}{2}\cdot\frac{\sqrt{2  }}{2},

    we can break it up and use ones we do know by using the addition formula

    sin(\frac{\pi}{6})=\frac{1}{2}

    cos(\frac{\pi}{4})=\frac{\sqrt{2}}{2}

    sin(\frac{\pi}{4})=\frac{\sqrt{2}}{2}

    cos(\frac{\pi}{6})=\frac{\sqrt{3}}{2}

    Now, use the addition formula to put it together

    It would appear that when we add them up we get

    \frac{\pi}{6}+\frac{\pi}{4}=\frac{5\pi}{12}

    So, sin(\frac{5\pi}{12})

    See how to do that now?. Sometimes they're not so obvious so we have to do some gymnastics.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Sep 2007
    Posts
    176
    sorry i didn't learnt that additon formula

    i don't understand how to get that
    <br />
\frac{\pi}{6}+\frac{\pi}{4}=\frac{5\pi}{12}<br />




    <br />
\frac{\pi}{6}+\frac{\pi}{4}=\frac{5\pi}{12}<br />
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Eater of Worlds
    galactus's Avatar
    Joined
    Jul 2006
    From
    Chaneysville, PA
    Posts
    3,001
    Thanks
    1
    addition formula for sine: sin(a+b)=sin(a)cos(b)+cos(a)sin(b)

    sin(\frac{\pi}{6}+\frac{\pi}{4})=sin(\frac{\pi}{6}  )cos(\frac{\pi}{4})+cos(\frac{\pi}{6})sin(\frac{\p  i}{4})=sin(\frac{5\pi}{12})
    Put them together from the last post. and you get

    \frac{\sqrt{3}+1}{2\sqrt{2}}\approx{0.965925....}

    or 75 degrees sin(75)=\frac{\sqrt{3}+1}{2\sqrt{2}}
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. find the ratio
    Posted in the Calculus Forum
    Replies: 3
    Last Post: November 19th 2009, 07:03 AM
  2. Find>trigo~!
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: September 16th 2008, 09:39 PM
  3. trigo >find angles
    Posted in the Trigonometry Forum
    Replies: 6
    Last Post: September 12th 2008, 06:17 AM
  4. trigo>find angle
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: September 11th 2008, 07:56 PM
  5. still trying to find the ratio
    Posted in the Geometry Forum
    Replies: 1
    Last Post: March 16th 2008, 05:20 PM

Search Tags


/mathhelpforum @mathhelpforum