Double Integrals Explained: How to Set Up and Evaluate Integrals Over Regions

This complete Woody Calculus lesson explains double integrals from the ground up. Learn the geometric meaning of ∬R f(x,y) dA, how Fubini’s Theorem turns double integrals into iterated integrals, how to identify Type I and Type II regions, how to reverse the order of integration, and when polar coordinates make the setup easier.

Continue Reading →

Green’s Theorem Explained: Why a Boundary Knows Everything Inside

Green’s Theorem turns a boundary line integral into an interior double integral. In this Woody Calculus visual lesson, learn how Green’s Theorem connects circulation, curl, flux, area, line integrals, double integrals, Stokes’ Theorem, and the Divergence Theorem in Calculus 3.

Continue Reading →

The Jacobian Explained: The Hidden Scale Factor in Calculus III

The Jacobian is the hidden scale factor behind every coordinate change in Calculus III. In this Woody Calculus visual lesson, learn how Jacobians explain area and volume scaling, change of variables, polar coordinates, cylindrical coordinates, spherical coordinates, double integrals, triple integrals, and why the mysterious extra factors r and ρ²sinφ appear.

Continue Reading →