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Thread: how to find the exact value of sin,cos and tan of an angle?

  1. #1
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    how to find the exact value of sin,cos and tan of an angle?

    find the exact values of the sine, cosine, and tangent of the angle.

    11π/12 = 3π/4 + π/6


    can you please explain how to do a question like this step by step.

    thank you ( i was not in school when this was done so I'm not sure how or where to start)
    Last edited by skeeter; Dec 7th 2012 at 04:47 AM. Reason: changed angel to angle
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  2. #2
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    Re: how to find the exact value of sin,cos and tan of an angle?

    Quote Originally Posted by Candy101 View Post
    find the exact values of the sine, cosine, and tangent of the angle.

    11π/12 = 3π/4 + π/6


    can you please explain how to do a question like this step by step.

    thank you ( i was not in school when this was done so I'm not sure how or where to start)

    Go to this webpage.
    Last edited by skeeter; Dec 7th 2012 at 04:46 AM. Reason: changed angel to angle
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  3. #3
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    Re: how to find the exact value of sin,cos and tan of an angle?

    the two angles on the right side of the equation are unit circle angles ... you should already know the values for sine, cosine, and tangent for each of them.

    plug and chug using the sum/difference identities ...

    \sin(a \pm b) = \sin(a)\cos(b) \pm \cos(a)\sin(b)

    \cos(a \pm b) = \cos(a)\cos(b) \mp \sin(a)\sin(b)

    \tan(a \pm b) = \frac{\tan(a) \pm \tan(b)}{1 \mp \tan(a)\tan(b)}
    Last edited by skeeter; Dec 7th 2012 at 04:47 AM.
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    Re: how to find the exact value of sin,cos and tan of an angle?

    i try sin

    sin(3pi/4)Cos(pi/6)+cos(3pi/4)sin(Pi/6)


    and i got



    √2/2 x √3/2 + -√2/2 x 1/2 = √6 - √2 /4 is this correct?
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  5. #5
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    Re: how to find the exact value of sin,cos and tan of an angle?

    Quote Originally Posted by Candy101 View Post
    i try sin

    sin(3pi/4)Cos(pi/6)+cos(3pi/4)sin(Pi/6)


    and i got



    √2/2 x √3/2 + -√2/2 x 1/2 = √6 - √2 /4 is this correct?
    here's an idea ... use your calculator to check your work.
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  6. #6
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    Re: how to find the exact value of sin,cos and tan of an angle?

    well i just wanted to know if I'm on the right track, and according to my calculator the answer is right, but i just wanted to know if that's the correct way.
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