Parametric equatons for tangent line at point [SOLVED]

jwpaine

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Mar 10, 2007
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Find parametric equations for the tangent line at the point
\(\displaystyle \((\cos(\frac{5 \pi}{6}) ,\sin(\frac{5 \pi}{6}) ,\frac{5 \pi}{6}) )\)\)
on the curve \(\displaystyle \(x=\cos t,\ y=\sin t, \ z=t\)\)

This is what I've done so far:

r(t) = <cos(t) , sin(t), t>
r'(t) = <-sin(t) , cos(t), 1>

So tangent line at r(t): L(t) = r(t) + tr'(t)

so since my point (x, y, z) = \(\displaystyle \((\cos(\frac{5 \pi}{6}) ,\sin(\frac{5 \pi}{6}) ,\frac{5 \pi}{6}) )\)\)

wouldn't the parametric equations for the tangent at the above point be:
x(t) = r(x) + tr'(x) (for x = cos(5(pi)/6))
y(t) = r(y) + tr'(y) (for y = sin(5(pi)/6))
z(t) = r(z) + tr'(z)

Thanks for any help

EDIT: Solved:

t = 5(pi)/6 for r(t) satisfies the given point
thus:

x(t) = r(t) + tr'(t)
x(t) = cos(5(pi)/6) - (1/2)t

and we do the same for y(t) and z(t)
 
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