A regular hexagon and 3 classes of convex hexagons, plus concave hexagons will tessellate.
It can be convex or concave.
A rhombus is an equilateral parallelogram. As such, it is neither concave nor convex.
Rectangle
convex
No
A regular hexagon and 3 classes of convex hexagons, plus concave hexagons will tessellate.
by shape
It depends on what the angles are. If any of the angles have measurements greater than 180 degrees, it is concave. If all angles are less than 180 degrees, then it is concave. For example, a regular hexagon has six 120 degree angles, so it is convex. If there was a hexagon with five 90 degree angles and one 270 degree angle, it would be concave.
A concave irregular hexagon can have up to 6 right angles. A convex irregular hexagon can have up to 3 right angles.
The opposite of convex is concave. Concave shapes have an inward curve, while convex shapes have an outward curve.
It can be convex or concave.
convex and concave
The answer depends on what you mean by size: its area (more likely) or perimeter. In either case, the answer depends on what information you have about the hexagon: whether it is regular, irregular but convex, or concave.
If it's a regular hexagon, it can't be concave. If it's an irregular hexagon,then it can be concave if it wants to, but it doesn't have to be.
A hexagon could be any of those, and more than one at the same time. If it's regular, then it's all the others except 'concave'. On the other hand, if it's concave, then it's not any of the others.
Lenses: converging (convex) and diverging (concave) Mirrors: concave and convex