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Math Help - What identities prove this statement is correct?

  1. #1
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    What identities prove this statement is correct?

    1 cos2x/(1 + Sinx) = Sinx?


    Thank you!
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  2. #2
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    Re: What identities prove this statement is correct?

    Is that \displaystyle \begin{align*} 1 - \frac{\cos^2{x}}{1 + \sin{x}} \end{align*}?
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    Re: What identities prove this statement is correct?

    That is a great question. I believe it is. I am taking an online pre-calc class and that is exactly how the question appears. The professor is not too helpful......He said this statement is true so i do think it is how you noted. Any help would be greatly appreciated
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    Re: What identities prove this statement is correct?

    Quote Originally Posted by DanielleNY View Post
    That is a great question. I believe it is. I am taking an online pre-calc class and that is exactly how the question appears. The professor is not too helpful......He said this statement is true so i do think it is how you noted. Any help would be greatly appreciated
    \displaystyle \begin{align*} 1 - \frac{\cos^2{x}}{1 + \sin{x}} &\equiv 1 - \frac{1 - \sin^2{x}}{1 + \sin{x}} \\ &\equiv 1 - \frac{\left(1 - \sin{x}\right)\left(1 + \sin{x}\right)}{1 + \sin{x}} \\ &\equiv 1 - \left(1 - \sin{x}\right) \\ &\equiv 1 - 1 + \sin{x} \\ &\equiv \sin{x} \end{align*}
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    Re: What identities prove this statement is correct?

    wow thank you so much for the quick reply!!!...I will definitely be visiting this forum a lot more
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