Do ( A ) please show all work

(3 points) (a) Find ALL the left cosets for the group D4 with the subgroup H = {1, R2}. Does this set of cosets form a group? Which familiar group is this isomorphism to? (b) Find ALL the left cosets for the group D4 with the subgroup H = {1, FR}. Does this set of cosets form a group? Which familiar group is this isomorphism to? (c) Find ALL the left cosets for the group Z12 with the subgroup H = {0,4,8). Does this set of cosets form a group? Which familiar group is this isomorphism to