2D - the triangle 3D - the tetrahedron (i.e. it has a triangle on each side and there are 4 sides.
A camera is a 3D shape. A photograph is a 2D projection of a 3D shape onto a 2D shape.
It's a 2D shape.
A television set is a 3D shape. The image (picture) on the television screen is a 2D shape. 3D is when it has length, width, and height. 2D is only length and width.
A piece of paper is 3D.
a pyramid is a 3D shape :)
tetrahedron is a 4 faced 3d shape.