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Math Help - Please help me how to solve this question.

  1. #1
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    Smile Please help me how to solve this question.

    Determine all the possible values where 0 degree <= x <= 360 degree such that;

    sin x sec x - 3 sin x = 0
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  2. #2
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    Re: Please help me how to solve this question.

    Hey choi105.

    Please show us what you have tried.
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  3. #3
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    Re: Please help me how to solve this question.

    sin x sec x - 3 sin x = 0
    sin x 1/cos x - 3 sin x = 0
    sin x - 3 sin x = cos x

    then i not sure the step correct or not...
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  4. #4
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    Re: Please help me how to solve this question.

    Hint: Try thinking in terms of tan(x).
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  5. #5
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    Re: Please help me how to solve this question.

    Quote Originally Posted by choi105 View Post
    sin x sec x - 3 sin x = 0
    sin x 1/cos x - 3 sin x = 0
    sin x - 3 sin x = cos x

    then i not sure the step correct or not...
    First of all, your third line is incorrect, since when you multiply everything through by \cos{(x)} you're supposed to get \displaystyle \sin{(x)} - 3\sin{(x)}\cos{(x)} \ 0.

    Anyway, you should factorise the entire expression first and set each factor equal to 0.

    \displaystyle \begin{align*} \sin{(x)}\sec{(x)} - 3\sin{(x)} &= 0 \\ \sin{(x)} \left[ \sec{(x)} - 3 \right] &= 0 \\ \sin{(x)} = 0 \textrm{ or } \sec{(x)} - 3 &= 0 \end{align*}

    Go from here...
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