For the position vectors r(t) compute the unit tangent vector T(t) for the given value of t.

A) let r(t) = .

Then T(pi/4) = <_,_>

B) let r(t) =

then T(3) = <_,_>

C let r(t) = e^2t*i + e^-3t*j + t*k

T(0) = _*i+_*j+_*k