t Find the arc length parameter along the given curve from the point where t= O by evaluating the integral s(t) = I|v(r)| (it. Then find the length of the indicated portion of the curve 0 TI r(t)=6costi+6sintj+6t k, where OStSZ' The arc length parameter along the curve, starting at t= O is s(t) = (Type an exact answer, using radicals as needed.)