Evaluate (if possible) the vector-valued function at each given value of t. (a) r(0) (b) r(/2) (c) r(s - ) (d) r( + t) -

Evaluate (if possible) the vector-valued  function at each given value of t.

(a) r(0) 

(b) r(π/2)

(c) r(s - π)

(d) r(π + Δt) - r(π)

r(t) = 3 cos ti + (1 - sin t)j - tk