Let O, A and B be the points (0,0,1), (1,0,1) and (0,1,1) respectively in the (x,y,z) plane. Let C be the closed curve OABO consisting of the line segment linking points O and A, followed by the quarter-circle x^2 + y^2 = 1 with centre the point O lying on the plane z = 1 and linking points A and B, followed by the line segment linking points B and O. Let F = (z - 2y)i - 2xj + xk. a) Calculate ∇ x F and comment on your result. b) Calculate the line integral ∧c F . dl (directly) where the curve C is transversed in the counter-clockwise direction as seen from above. Hint: You may find the following trigonometric identity useful: cos 2θ = cos^2θ - sin^2θ. c) By constructing a suitable potential function show that F is conservative. Hence confirm your result in part (b) above.