# How to make a polyhedron?

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The need to make a polyhedron occurs infrequently, but it happens that a child is given this task or you decide to make an original gift to a friend. Or perhaps you had some design idea. One way or another, a paper polyhedron was needed. How to glue it?

## Making a polyhedron out of paper

To make the process of work easier to describe, we will tell you how to make a triangular pyramid or a tetrahedron ABCD out of paper. This is a figure with four sides in the form of equilateral triangles. For the work we need:

- thick paper
- pencil,
- ruler,
- compasses or protractor
- scissors,
- glue.

First, draw on paper closer to the bottom edge of the sheet (but not on the very edge!) The base of the tetrahedron is an equilateral triangle ABC. It will be more convenient to draw it top down, but this is not the point.

To make the triangle really equilateral, it is best to use a ruler and compass. We draw a straight line, on it we cut off the segment AB, equal to the side of the triangle.Points A and B will be two vertices of a triangle. Then we draw with a compass two arcs of the same exact size with centers at points A and B. At the intersection of the arcs there will be a third vertex C.

If you do not want to work with compasses, you can use a protractor. The angles in an equilateral triangle are 60 degrees. From points A and B we draw rays at an angle of 60 degrees to the segment. The point of their intersection will be the top of S.

The base is. Now you need to add three more exactly the same triangles to it - the side faces of the tetrahedron. The principle of construction of triangles remains the same, only as the base of the new triangles-faces we take already drawnside abc. We will have three more triangles: AVD`, BDD`` and CAD```.

We will need to collect all three vertices D`, D``, D``` into one point D and glue the shape. For gluing, you will need to draw additional strips of paper about 0.5 cm wide to the sides A D `, B D`` and C D``.

Now you can cut the resulting shape, bend it neatly along all the lines, spread some additional strips with glue and glue it together.

The development of more complex shapes is done in the same way. But if you do not want to think for yourself, you can find ready-made on the Internet.For example, here are the scans of several figures at once.