Use Green's Theorem to evaluate

Question

F · dr.
C
(Check the orientation of the curve before applying the theorem.)
F(x, y) =
y cos x − xy sin x, xy + x cos x
, C is the triangle from (0, 0) to (0, 12) to (3, 0) to (0, 0)

Answer 1

I recall Green's Theorem in x-y coordinates, but you seem to be asking for polar coordinates, yet give F in terms of x and y.

Am I not getting something here?