Quitting smoking = depression? I quit smoking cigarettes seven days ago. I've quit before and I understand that this horrible loneliness and depression are just some of the withdrawal symptoms, but I don't know how to lessen the depression. Most of my friends are smokers, so I'm not going out much and I live alone.
A tessellation is a regular pattern made up of flat shapes repeated and joined together without any gaps or overlaps. These shapes do not all need to be the same, but the pattern should repeat. Another word for tessellation is tiling.
Any triangle or quadrilateral (even non-convex) can be used as a prototile to form a monohedral tessellation, often in more than one way. Copies of an arbitrary quadrilateral can form a tessellation with translational symmetry and 2-fold rotational symmetry with centres at the midpoints of all sides.