Free Tools · Geometry
Cross Section Lab
Pick a solid, then tilt, spin and slide the cutting plane. The cut face lights up in 3D and the panel shows the cross section flattened out, named and measured. Drag to orbit the solid; scroll over it to slide the plane.
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Why this matters on the SAT and ACT
Cross section questions are short, but they are hard to picture. A plane through a cube can give a triangle, a rectangle, a pentagon or even a regular hexagon depending on where it cuts. A plane through a cone gives a circle, an ellipse, a parabola or a hyperbola depending on its angle.
Try the presets first, then move the plane slowly through each solid. Watch when the shape changes name and ask yourself why. The area and perimeter readouts use the real dimensions, so you can check a worked problem against them.
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