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# Nets solids of revolution. How to make pdf template What happens if a flat geometric shape, such as a rectangle, begins to rotate rapidly relative to one of its sides?
We create a new geometric solid in space by rotation.

The sides of a rotating rectangle form the side surfaces of the cylinder. The official definition for such geometric solids is as follows:

# The solids of revolution are volume solids that arise when a flat geometric figure bounded by a curve rotates around an axis lying in the same plane. Here it is important that a flat geometric figure can be a completely arbitrary shape.

For example, a curve that, when rotated, forms a vase or a light bulb. Such tools for creating bodies of revolution are very popular with those who work in 3D-design programs. But from a mathematical point of view, the following geometric solids of revolution are of primary interest to us:

The cone is formed by a rectangular triangle rotating around one of the sides.
A truncated cone is part of the cone located between its base and the cutting plane parallel to the base. It is formed by rotating a rectangular trapezoid around its side, perpendicular to the trapezoid bases. The ball is formed by a semicircle rotating around the diameter of the cut.
During the rotation of the figures' contours, a surface of revolution arises (for example, a sphere formed by a circle). During the rotation of filled contours, bodies appear (like a ball formed by a circle). An ellipsoid is a surface in three-dimensional space, obtained by deforming a sphere along three mutually perpendicular axes.
The torus is formed by a circle rotating around a straight line that does not intersect it.
The usual sense of the torus is a "bagel".
A paraboloid is a surface formed due to a rotation around the axis of a curve formed by a parabola graph. Hence the name paraboloid.
A hyperboloid is a surface formed due to rotation around the axis of a curve formed by a hyperbola graph. Accordingly, the name is a hyperboloid.

To compare the resulting models' sizes, we tried to assemble them on the same surface together with prisms from the Magic Edges #16 issue. It turned into a whole mathematical city of paper that fits on the table!

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