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Math Help - Give the exact value of the following (no calculators) :

  1. #1
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    Give the exact value of the following (no calculators) :

    cos (sin^-1 1/4 - tan^-1 (-3) )

    Note: I posted a picture below with my work and i wanted to see if i'm correct, if not, please help me out, thanks!!! <3
    Attached Thumbnails Attached Thumbnails Give the exact value of the following (no calculators) :-cherish-math-170-quiz-7.jpeg  
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  2. #2
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    Re: Give the exact value of the following (no calculators) :

    cosx =1/sqrt15

    cosy=1/sqrt 10

    sinx=1/4

    siny=-3/sqrt10


    nw apply cos(x-y) ,u get 1/sqrt150 - 3/4sqrt10
    Thanks from boltage619
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  3. #3
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    Re: Give the exact value of the following (no calculators) :

    Thanks, can you help me out with my other post? =P
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    Re: Give the exact value of the following (no calculators) :

    which one will try
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    Re: Give the exact value of the following (no calculators) :

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  6. #6
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    Re: Give the exact value of the following (no calculators) :

    Hello, boltage619!

    \text{Solve over the interval }(0^o,\,360^o)\!: \;10\sin^2\theta - 13\sin\theta - 3 \:=\:0

    Factor: . (2\sin\theta - 3)(5\sin\theta + 1) \:=\:0


    We have two equations to solve . . .

    2\sin\theta - 3 \:=\:0 \quad\Rightarrow\quad \sin\theta \:=\:\tfrac{3}{2} \quad\Rightarrow\quad \text{No real roots}

    5\sin\theta + 1 \:=\:0 \quad\Rightarrow\quad \sin\theta \:=\:\text{-}\tfrac{1}{5} \quad\Rightarrow\quad \theta \:=\:\sin^{\text{-}1}\left(\text{-}\tfrac{1}{5}\right)
    . . \theta \:=\:-11.53695903 \quad\Rightarrow\quad \theta \:=\:\begin{Bmatrix}191.5^o \\ 348.5^o\end{Bmatrix}
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