University Maths Notes: Calculus – Green's Theorem
Green's theorem gives the relationship between a line integral
around a simple closed curve
and
a double integral over the plane region
bounded
by
It
is the two-dimensional special case of the more general Stokes'
theorem, and is named after British mathematician George Green.
Let
be
a positively oriented (counterclockwise), piecewise smooth, simple
closed curve in the plane
and
let
be the region bounded by
If
and
are
functions of
defined
on an open region containing
and
have continuous partial derivatives there, then![]()

For example let
be
the triangular region illustrated below and let![]()
![]()
We need to find the limits. If we integrate with respect to
first
then we must find
as
a function of
on
the line BC:
Our
integral becomes
![]()
Expanding the integrand and simplifying gives
![]()
![]()