K Solve the following initial value problem for r as a function of t. Differential equation: Initial condition: r(t)=++k i+ dr = (4 tant)i + cos dt r(0) = 21-3j+2k j-(sec 3t)k Find the curve's unit tangent vector. Also, find the length of the indicated portion of the curve. r(t) = (5cos t)i + (5sin t)j + (7t)k, Osts* Find the curve's unit tangent vector. T() = +i+k TID Find the curve's unit tangent vector. Also, find the length of the indicated portion of the curve. r(t) = 9ti + 3/2k. Osts40 ++ k. The curve's unit tangent vector is (Type exact answers, using radicals as needed.).