Area between two curves

MathematicsCalculusAges 17–18

Pick a pair of curves and watch the plane region between them get shaded. The simulation splits the region into thin strips to show that ∫(f − g)dx is the limit of the sum of strip areas as the number of strips grows, and it warns when the two graphs swap which one is on top within the interval, so the integral must be split by the sign of f − g.