f o of =0, then | dy =0. x ). Prove that is a function f is harmonic b). Using Green's Theorem, evaluate the line integral - y dx+ + y dy where C = C, +C, e is the boundary of the region R that is inside the circle x=5cos 0, y=5sin0 and outside the eclipse x= 2 cos 0, y = sin 0. c). Find the surface in the accompanying of the helicoid area r(r,0)=(rcos0)i+(r sin 0) j+Ok, 0