Problem 4: [30 pts] Suppose that r (#) = (3 cos(at), 3 + 213/2, 3 sin(at) ) traces out a curve C in R". A. [10 pts] Find a vector whose magnitude is 4 and whose direction is orthogonal to both r (2) and r '(2).B. [5 pts] Explain why the curve traced out by r (t) is not parameterized by arclength.Recall that r (t) = (3 cos(at), 3 + 2t /2, 3sin(at) ) traces out a curve C in R C. [15 pts] Find a parameterization of C that uses arclength as a parameter