(10 points (bonus)) Let vec(f):[a,b]Rn be a twice differentiable function with Dvec(f)(t)vec(0) for all tin[a,b]. Suppose t0 is a point in (a,b) such that the curve parametrized by vec(f) reaches the farthest point from the origin.(a)(5 points) Prove that vec(f)(t0) and Dt0vec(f)(t) are orthogonal.(b)(5 points) Prove that the curvature of the curve vec(f) parametrizes at the point vec(f)(t0) is at least 1||(vec(f))(t)||.