Let
P(x,y,z),Q(x,y,z)
, and
R(x,y,z)
have continuous first partial derivatives on
R^(3)
. Let
C
be a closed smooth curve without self intersection, let
S
be a smooth surface which can be injectively projected onto the
xy
-plane and whose boundary is
C
, and let
hat(n)
be the unit normal to
S
chosen thusly: If when traversing
C,S
is on the left, then put
hat(n)
on that side. If when traversing
C,S
is on the right, then put
hat(n)
on the other side. (Think right hand rule.) Use Green's Theorem to prove that
o\int_C Qdy=∬_(S)((delQ)/(delx)(hat(k))-(delQ)/(delz)(hat(i)))*hat(n)dS