Section
It is the shape obtained by cutting a solid with a plane. It is found by intersecting the plane with each face.
Section of a cube by a horizontal plane
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Solid and cutting plane
The cutting plane is horizontal, at mid-height. In the elevation it looks like a line; in the plan it is not seen (it is parallel to it).
True size of the section
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The section, in projection
When the cutting plane is oblique, the section looks distorted in both views. The plane must be rotated flat to see it as it is.
General method for sections
When the cutting plane is not projecting:
- Change the projection plane so the cutting plane is seen edge-on: the new ground line is perpendicular to its trace.
- In that view the section looks like a segment: mark the points where it cuts the edges of the solid.
- Carry the points to the other views with reference lines and join them in order.
- To see the section in true size, rotate the cutting plane flat or make a second change of plane parallel to it.