Let it be D Level R2 an area on the edge of which 81) is parameterization ( ) II x r = 1 + r3 rt : U 1:2 ya) : 3 1 + r Check that the curve C is closed and defines a level range D area. Help: Select such a vector field F(x,y) : F1(x,y)i +F2(x,y)jthat 6F2 6F1 6x y and apply Green's theorem