is a square a 3d shape
There can be no closed 3D shape with only one square and 3 triangles.
square
It's a 2D shape.
A 3d shape with 5 faces can be a square pyramid
A cube
No, a square is a 2d shape, although a 3d shape can be made using multiple squares at different angles than 180 or 0 to each other.
A square or rectangular based pyramid is a 3D shape with 5 corners or points. It also has 4 triangular flat flaces, one square/retangular face and 8 straight edges.
only if it is in a certain shape, although the 3d shape would not look exactly like the 2d one, take this, if a square were to be turned into a square, it would have to be extended, but if you were to do this it would just stay as a 2d square, in a 3d world, but if it were a net (like the t cube) then yes, it would be able to become 3d
take, for an example, a duck. This is a 3d shape because it has three dimensions. Compare this to a square, which is 2d. the difference is that the duck has a beak, and the square does not.
The simplest such shape is PYRAMID.
It is the 3D shape cylinder