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Math Help - Solving for theta

  1. #1
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    Solving for theta

    Ok.. so I've been stuck on a problem for a while now and have no clue how to even start this problem

    it's 3sin^2X+5cosX=4

    It would be much appreciated if someone could explain to me how I even start to solve this problem
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  2. #2
    Behold, the power of SARDINES!
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    Quote Originally Posted by StephAnnie View Post
    Ok.. so I've been stuck on a problem for a while now and have no clue how to even start this problem

    it's 3sin^2X+5cosX=4

    It would be much appreciated if someone could explain to me how I even start to solve this problem
    You need to use the Pythagorean identity

    \sin^2(x)=1-\cos^2(x) this reduces the equation to

    3(1-\cos^2(x))+5\cos(x)-4=0 \iff 3\cos^2(x)-5\cos(x)+1=0

    So this is quadratic in form. Can you finish from here
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  3. #3
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    Thank you soo much for your help!!
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