2
It must have at least one.
5
A triangular prism has five faces.
A triangular prism has 9 edges!
there are two plane symmetry on triangular prism.
2
It must have at least one.
This depends on the type of prism. If the shapes on the ends are pentagons, the prism has 6 planes of symmetry. If they are hexagons, it has 13 planes of symmetry. It has the same number of planes of symmetry as the shapes on the end have lines of symmetry, plus 1.
Five
3
Three.
5
A triangular based pyramid has no lines of symmetry. However, if each of the non-base triangular sides are equal it will have 3 planes of symmetry. If the base triangle is also equal, it will have 6 planes of symmetry.
Three.
3D shapes don't have lines of symmetry they have plane's of symmetry.
The answer is 13- for more detail: