To verify the result above, disassemble the closed path C as the following: . C1 : the directed line segment from (0, 0) to (3, 0), . C2 : the counterclockwise quarter circle from (3, 0) to (0, 3), . C3 : the directed line segment from (0, 3), (0, 0). Evaluate each of the following line integrals: . 11= yx dx + xy dy C . 12 = y x da + xy dy J C2 . 13 = yx dx + x y dy C'3