1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Unit tangent vector (cal 3)

  1. Sep 27, 2005 #1
    positon vectors r(t) find the unit tangent vectors T(t) for the given value of t

    r(t) = (cos5t, sin5t)
    T(pi/4) = ( , )

    r(t) = (t^2, t^3)
    T(1) = ?

    r(t) = e^5t i + e^-1t j + t k
    T(2) = ? i+ ? j+ ? k

    now the to find it i use r'(t)/lr'(t)l
    I did that, but i get wrong answers i dont know what im doing wrong cuz all i c is that is how u find the unit tangent vectors... someone plz help me and explain what u did.. thanks alot!
  2. jcsd
  3. Sep 27, 2005 #2
    the derivative is the tangent vector.
    then divide it by its magnitude to get unit tangent vector.
  4. Sep 27, 2005 #3
    I did that and the damn computer say i got the wrong answers.... like the 1st one i took it derivative then i divid it by its magnitude which is squaring everything and sq rt it right thats what i did..
  5. Sep 27, 2005 #4
    give the answer that you have found for the first one.
  6. Sep 27, 2005 #5
    well i worked out the second one i got (1, 1) i really im doin something stupid
  7. Sep 27, 2005 #6
    i get 2/sq rt of 13, 3/ sq rt of 13
    what is wrong with your steps?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook