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Math Help - finding the equation of a tangent

  1. #1
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    finding the equation of a tangent

    i for the x and y value but i need help finding the slope.

    the equation is f(x) = tanx at x=pi/4

    i know the derivative of this is sec^2(x)

    so y = sec^2(pi/4)

    i dont know how to get the value of this
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  2. #2
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    Quote Originally Posted by proski117 View Post
    i for the x and y value but i need help finding the slope.

    the equation is f(x) = tanx at x=pi/4

    i know the derivative of this is sec^2(x)

    so y = sec^2(pi/4)

    i dont know how to get the value of this
    \frac{\pi}{4} is on the standard triangle. sec^2(x) = \frac{1}{cos^2(x)}

    As cos{\frac{\pi}{4}} = \frac{\sqrt(2)}{2} so

    cos^2{\frac{\pi}{4}} = \frac{1}{2}

    therefore cos^2{\frac{\pi}{4}} = 2
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