This (free) educational project has been created by Laurin Gschnitzer (15 years of age).
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MathematicsVector Calc

Green's Theorem

∮ P dx + Q dy = ∬ (∂Q/∂x − ∂P/∂y) dA

Relates a line integral around a closed curve to a double integral over the enclosed area.

More detailed explanations, examples and illustrations for this entry are coming soon.