Green’s theorem also says we can calculate a line integral over a simple closed curve C based solely on information about the region that C encloses. Green’s theorem says that we can calculate a double integral over region D based solely on information about the boundary of D. Green’s theorem takes this idea and extends it to calculating double integrals. Figure 6.32 The Fundamental Theorem of Calculus says that the integral over line segment depends only on the values of the antiderivative at the endpoints of.