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Math Help - Solving trigonometric equations?

  1. #1
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    Solving trigonometric equations?

    Can anyone show me how to solve these two equations
    sin2x=-sinx between 0 and 360 degrees

    also

    sinxtanx-sinx=0

    I am not sure how do these.
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  2. #2
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    Quote Originally Posted by homeylova223 View Post
    Can anyone show me how to solve these two equations
    sin2x=-sinx between 0 and 360 degrees
    Note that sin(2x) = 2 sin(x) cos(x), so
    2 sin(x) cos(x) = -sin(x)

    2 sin(x) cos(x) + sin(x) = 0

    sin(x) [2 cos(x) + 1] = 0

    Can you take it from there?

    -Dan
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  3. #3
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by homeylova223 View Post
    sinxtanx-sinx=0
    sin(x) tan(x) - sin(x) = 0

    sin(x) [ tan(x) - 1 ] = 0

    etc.

    -Dan
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  4. #4
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    You are really skilled in math.
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  5. #5
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by homeylova223 View Post
    You are really skilled in math.
    No really. I'm blushing...

    -Dan
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