5) (From Hardcover Book, Marsden/Tromba, Vector Calculus, 6th ed., Section 2.4., # 6) Give a parameterization (a) for the graph of f (ac) = a2 (b) for the ellipse given by + 25 = 1 6) (From Hardcover Book, Marsden/Tromba, Vector Calculus, 6th ed., Section 4.1., # 20) Show that, at a local maximum or minimum of ||r(t) ||, the vector r (t) is perpendicular to r(t)