(b) Evaluate ds 2. (Marsden-Tromba 7.1.25) Compute the path integral of f(x, y, z) = xyz along the path x(t) = cos (t), y(t) = sin (t), z(t) = t, te [0, "]. Hint: You may want to try integration by parts, along with the identity sin (2x) = 2 sin (x) cos (x)