2. Evaluate the closed line integral of the vector field F= y x + xyy along the edge of the rectangle -1x1, 0Sys1 using the Stokes' theorem. The direction of the integration is counter-clockwise. 3. Consider the vector field F=-2yx . Compute the line integral along the upper half of the unit circle in the counter-clockwise direction by (a) directly carrying out the integral, and (b) using the Stokes' theorem