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Math Help - Identity troubles...

  1. #1
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    Identity troubles...

    I'm reviewing for a test and I came across this problem:

    Simplify: sec(x)cot(x)sin(2x)

    I've been trying different things for about an hour, but I can't figure out how to get 2cos(x) which is the answer in the back of the book. Could anyone help me get started?
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by rads View Post
    I'm reviewing for a test and I came across this problem:

    Simplify: sec(x)cot(x)sin(2x)

    I've been trying different things for about an hour, but I can't figure out how to get 2cos(x) which is the answer in the back of the book. Could anyone help me get started?
    It's actually a one step problem

    \sec x \cot x \sin 2x = \frac {1}{\cos x} \cdot \frac {\cos x}{ \sin x } \cdot 2 \sin x \cos x  = 2 \cos x

    what things were you trying?
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  3. #3
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    Thanks. I found the problem. In my first attempt I made a simple mistake and incorrectly derived that...

    \frac {1}{\cos x} \cdot \frac {\cos x}{\sin x} = \sin x and not \frac {1}{\sin x}

    Leading to overcomplication of the problem and frustration in future attempts. Seeing it on the computer made it clear compared to my rather inconsistent handwriting.
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