6. Verify Stokes' theorem for the vector field \(\overrightarrow{F}(x,y,z)=z\hat{i}+x\hat{j}+y\hat{k}\) taken over the half of the sphere x^2+y^2+z^2=a^2 lying above the xy-plane; where C is the boundary of this sphere on the surface z=0 with anti-clockwise orientation looking down the positive z-axis.