Sectional views and true shapes

When you cut through a 3D object like a cylinder or cone with a plane, you create a section. The true shape of that section is what you actually see when you look directly at the cut surface. For example, if you slice a cylindrical tin of Milo horizontally, you get a circle. But if you slice it at an angle, you get an ellipse instead.

Different angles of cutting produce different shapes. A cone cut horizontally gives a circle, but sliced at an angle gives an ellipse. Cut through both halves and you get a parabola. Understanding these true shapes requires you to visualize the 3D object and imagine exactly how the cutting plane intersects it.

The key is drawing the section accurately on your technical paper by finding where edges meet the cutting plane.