Nets of three-dimensional solids

# Nets of three-dimensional solids

In the following it is a good idea to use paper to form the nets.

#### Question 1

Which net when folded makes a triangular-based pyramid?

Detailed description of diagram

#### Solution

The faces of a pyramid, other than the base face, are triangles.

Here are pictures of 3 different types of pyramids.

Detailed description of diagram

square-based pyramid | hexagonal-based pyramid | triangular-based pyramid |

It can only be the second or the fourth net.

Looking at the drawing of the triangularâ€“based prism we see that that the number of edges/faces meeting at a vertex is 3. The second net has 4 faces meeting at a vertex. So the fourth net must be the one that makes a triangular-based pyramid.

When a triangular-based pyramid has all of its triangular faces the same (congruent) it is called a **tetrahedron**.

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