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Parametric equation Length of Curve?

Consider the parametric equation

x=19(costheta+thetasintheta)

y=19(sintheta-thetacostheta)

What is the length of the curve for theta =0 to pi/2?

4 Answers

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  • beem
    Lv 4
    5 years ago

    Length Of Curve Equation

  • 4 years ago

    ds = ?(4/9 + 16t^2/(t^2-9)^2) dt = (4/9)(t^2+9)/(t^2-9) for this reason the arc length of the curve (no longer of the equation!!!!!) is the quintessential of this expression from 4 to 5. This equals 4/9 cases a million + [3(ln((t-3)/(t+3))] the position the 2d time period is from 4 to 5, giving us the curve length of (4/9)(a million + 3 ln(7/4)).

  • kb
    Lv 7
    9 years ago

    Since x' = 19(-sin t + (sin t + t cos t)) = 19t cos t

    and y' = 19(cos t - (cos t - t sin t)) = 19t sin t, we have √((x')^2 + (y')^2) = 19t.

    Hence, the arc length equals

    ∫(t = 0 to π/2) 19t dt = 19π²/8.

    I hope this helps!

  • 9 years ago

    Let t = theta for simplified typing.

    dx/dt = 19*(-sin(t) + t*cos(t) + sin(t)) = 19t*cos(t)

    dy/dt = 19*(cos(t) + t*sin(t) - cos(t)) = 19t*sin(t)

    Length = ∫√(dx/dt)² + (dy/dt)² dt from 0 to pi/2

    = ∫19t dt from 0 to pi/2

    = 19/2 * (pi²/4) = 19pi²/8

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