For each of the following sums of reciprocals, state whether or not it corresponds to a regular or semiregular
tiling or a Platonic solid or Archimedean solid.
If it does, give the formal name of the tiling or solid and briefly explain (in just a few words) what the
name means. If it does not, state briefly why not.
(a) 1/3 +1/3

(b) 1/3+1/9+1/18

(c) 1/4+1/8+1/8

(d) 1/6+1/6+1/6

(e) 1/4+1/4+1/7