8. Evaluate $$\int F \cdot dr$$ both directly and by Green’s Theorem. The vector field and the region D is the upper half of a disk of radius a: $$0 \leq x^2 + y^2 \leq a^2$$ , $$y$$ . The curve C is the boundary of D and oriented counter-clock wise.
I got an answer of 0 using the direct way...