In Geometry, cross-section is the shape made when a solid is cut through by a plane. The cross section of a circular cylinder is a circle.

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There are also cross-sections that are ellipses or rectangles.

Hans Joachim Leutheusser has written:

'The effect of cross-section geometry upon the resistance to flow in conduits'

The cross section geometry/shape of a wing is called as Airfoil in American English the same is called as Aero foil in British English.

A cylinder has a circular cross section that is parallel to its base.

Not a right cross-section.