Consider the vector field F(x, y, z) = xi+yj+zk. a) Find a function f such that F = Vf and f(0, 0, 0) = 0. f(x, y, z) = b) Use part a) to compute the work done by F on a particle moving along the curve C' given by r(t)=(1+2 sint)i + (1+5 sin t)j + (1+3 sin 3t)k, 0