Nets of three-dimensional solids

Possible nets for a tetrahedron

There are only 2 possible nets for a tetrahedron. These are shown below.

1st tetrahedron net formation is 4 smaller triangles joined together to form a larger equilateral triangle.

2nd tetrahedron net formation is 4 equal equilateral triangles in a strip.

Note: There are 4 triangles which are all the same (4 congruent equilateral triangles). When the net is folded into a tetrahedron at each vertex there are three edges/faces meeting. These are the only two configurations of 4 such triangles that form a net for the tetrahedron.

Try some others to convince yourself that this is true.