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Math Help - Sine rule!

  1. #1
    Newbie
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    May 2009
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    Sine rule!

    Hi I have a question about one exercise. (See Atachment!) I do not get it how I have to calculate it.

    Could someone help me?

    a b c
    -- --- ----
    SinA SinB SinC

    a b 34
    ---- ---- -----
    sin45 sin60 SinC and now?
    Attached Files Attached Files
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  2. #2
    Junior Member
    Joined
    Apr 2009
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    Montréal
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    Quote Originally Posted by Justin12 View Post
    Hi I have a question about one exercise. (See Atachment!) I do not get it how I have to calculate it.

    Could someone help me?

    a b c
    -- --- ----
    SinA SinB SinC

    a b 34
    ---- ---- -----
    sin45 sin60 SinC and now?
    \frac {sinA}{a} = \frac {sinB}{b} = \frac {sinC}{c}

    \frac {sin45}{a} = \frac {sin60}{b} = \frac {sinC}{34}

    You know that C = 75° (180° - 45° - 60°, which is the sum of all angles in a triangle (180°) minus the two angles you have)

    \frac {sin45}{a} = \frac {sin60}{b} = \frac {sin75}{34}

    Rest is simple algebra. If you still need help simplifying, tell me.
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  3. #3
    Junior Member
    Joined
    Apr 2009
    From
    Montréal
    Posts
    45
    Just in case, before I leave, I'll post the answer as a spoiler, if you want to verify your equations and/or your answer.
    Spoiler:

    \frac {sin45}{a} = \frac {sin60}{b} = \frac {sin75}{34}

    \frac {sin45}{a} = \frac {sin60}{b} \approx 0,0284

    \frac {sin45}{a} \approx 0,0284

    a = \frac {sin45}{0,0284}

    a \approx 24.89


    \frac {sin60}{b} \approx 0,0284

    b = \frac {sin60}{0,0284}

    b \approx 30.49
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