a part below the axis gives a negative integral, so take its size
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Area between a curve and the Y-axisBetween x=g(y), the Y-axis and y=c,y=d, the area is ∫cd∣x∣dy: integrate along y with horizontal stripsLocked
Areas of circles, ellipses and parabolasUse symmetry: find one quarter and multiply; the ellipse a2x2+b2y2=1 encloses πab, using ∫0aa2−x2dx=4πa2Locked
Area between two curvesFind where the curves meet, then integrate (upper − lower) dx between those points, or (right − left) dyLocked