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Thread: Trig Proof

  1. #1
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    Trig Proof

    Could someone show me the first couple of steps of this Proof.


    2/1+cosx - tan^2(x/2) = 2cosx/1+cosx.

    Im working with the left side. I know to use Half-Angle I.D. I've tried all 3 tan Half angles. just keep getting hung up.
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  2. #2
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    Quote Originally Posted by Brndo4u View Post
    Could someone show me the first couple of steps of this Proof.


    2/1+cosx - tan^2(x/2) = 2cosx/1+cosx.

    Im working with the left side. I know to use Half-Angle I.D. I've tried all 3 tan Half angles. just keep getting hung up.
    \displaystyle \frac{2}{1+\cos{x}} - \tan^2\left(\frac{x}{2}\right) = \frac{2\cos{x}}{1+\cos{x}} is not an identity.

    let \displaystyle x = \frac{\pi}{2} and see what happens.

    fyi , the left side = 1 for all defined values of x.
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  3. #3
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    I understand that it is not an equation. I need to verify that one side equals the other.
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  4. #4
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    Quote Originally Posted by Brndo4u View Post
    I understand that it is not an equation. I need to verify that one side equals the other.
    but one side does not equal the other ... are you trying to solve the equation for a specific value of x ?
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