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Math Help - [SOLVED] Trigonometric Identities

  1. #1
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    [SOLVED] Trigonometric Identities

    given cos2y = 2 - sec^2(y)/sec^2(y)

    verify that each equation is an identity

    my mind is very boggling right now so please can anyone help with the steps?
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  2. #2
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    start with this double-angle identity ...

    cos(2\theta) = 2\cos^2\theta - 1
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  3. #3
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    i am sorry but i'm still stuck because i dont know what to do from there on, i've tried different identities but i don't think its leading to the right one.
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  4. #4
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    \frac{2 - \sec^2{y}}{\sec^2{y}} =

    \frac{2}{\sec^2{y}} - \frac{\sec^2{y}}{\sec^2{y}} =

    2\cos^2{y} - 1
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  5. #5
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    oohh..haha i guess i was thinking too hard and missed the simple steps.. thanks you very much
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