題組內容

3. A two-dimension vector field \( \vec{v} = \frac{x^2 - y^2}{(x^2 + y^2)^2} \vec{i} + \frac{2xy}{(x^2 + y^2)^2} \vec{j} \) ,


(a) Calculate by direct integration of around the circular closed coutour of radius 1 centered at the origin.(10%)