it makes a dimond
the shape that can make two smaller triangles is parallelogram.
Two triangles
The two triangles would make either a square or a rectangle.
All of them.
Two triangles can but its an irregular shape
Those would be SIMILAR triangles.
A triangular prism, where the two ends are triangles.
There are quite a few. Circles, squares, triangles...
Triangular prism
A rhombus.
Same size and shape
square