2. (a) Let f(x,y) = x2 - y2. Find / f ds where C is a circle of radius 2 centered at the origin. (b) Evaluate / (x + yz) dx + 2x dy + xyz dz, where C consists of line segments from (1, 0, 1) to (2, 3, 1) and from (2, 3, 1) to (2, 5, 2). (c Find the work done by the force field F(x, y) = (y?/x2) i - (2y/x) j in moving an object from P(1, 1) to Q(4, -2) along a smooth curve in the half plane x > 0. (d) Determine whether or not the vector field F(x, y) = (2.x cosy - y cosx)i + (-x2 sing - sin ac) j is a conservative vector field, if it is, find a function f such that F = Vf