# Math Help - r(t) = , t, e^t*cost, e^t*sint> find curvature at (0,0,1)

1. ## r(t) = , t, e^t*cost, e^t*sint> find curvature at (0,0,1)

i got r'(t) = <1, e^t(cos t - sin t) , e^t(sin t + cos t)>

r''(t) = <0, -2e^t(sin t), 2e^t(cos t)>

but i can't find any t which gives (0,0,1)?

2. ## Re: r(t) = , t, e^t*cost, e^t*sint> find curvature at (0,0,1)

Yes, when t= 0, r= < 0, 1, 1> so the curve does NOT go through (0, 0, 1). I suspect the problem was supposed to say "at (0, 1, 1)".