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Math Help - Identitiess!

  1. #1
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    Identitiess!

    Show that 1+tan^2t = sec^2t and show that sin2t=2sintcost

    Thankss!
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  2. #2
    ynj
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    Quote Originally Posted by lolalovepink View Post
    Show that 1+tan^2t = sec^2t and show that sin2t=2sintcost

    Thankss!
    1+tan^{2}t=1+\frac{\sin^{2}t}{\cos^{2}t}=\frac{\co  s^{2}t+\sin^{2}t}{\cos^{2}t}=\frac{1}{\cos^{2}t}=\  sec^{2}t
    for the \sin 2t=2\sin t\cos t,I assume you know that \sin x+y=\sin x\cos y+\cos x\sin y. Then it would be directly followed. If you have not learned this yet, it would become a very complex geometric proof.
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