please solve the attached

a). Prove that is a function f is harmonic =0, then dx - of dy = 0. ax 2 oy dy Ox b). Using Green's Theorem, evaluate the line integral ( e /2 -y dx+ e /2 +y dy where C= C, +C, is the boundary of the region R that is inside the circle x =5cos0, y=5sin@ and outside the eclipse x =2cos 0, y = sin 0. c). Find the surface area in the accompanying of the helicoid r(r,0) =(rcos0)i+(rsin0) j+ 0k, OSOS27, Orsl. 2TT (1, 0, 2TT) (1, 0, 0)