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Math Help - Trig

  1. #1
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    Trig

    If sinx/siny=1/2 and cos x/cosy=3 provethat
    sin(x+y)=7/3 sin x cosx
    Last edited by Tiger; December 5th 2009 at 09:45 PM.
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Tiger View Post
    If sinx/siny=1/5 and cos x/cosy=3 provethat
    sin(x+y)=7/3 sin x cosx
    I don't think what you wrote is correct

    sin(x + y) = sin(x)cos(y) + sin(y)cos(x)

    replacing cos(y) and sin(y) with their equivalent expressions from the given equations, we can write sin(x + y) in terms of sin(x)cos(x). But the answer you gave won't be the right one.
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  3. #3
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    Yeah made a mistake.
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  4. #4
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by Tiger View Post
    Yeah made a mistake.
    ok, well, do as i said and you will get the answer.
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