Hi all

Got this question but dont know where to start - need to get this in by tonight:

The Group D8 (i.e. a regular Octagon with 8 sides) has 5 distinct sub-groups of order 4. What I need to do is find one cyclic sub group and one non-cyclic subgroup and also give their generators, or elements in standard form.

Any ideas?

Are the elements of the subgroup: {e, r, r^2, r^3, r^4, r^5, r^6, r^7, s, sr, sr^2, sr^3, sr^3, sr^4, sr^5, sr^6, sr^7}

Please please help on this one - ive posted group theory and geometry questions here before but had little luck in answers these past few weeks.

Cheers

Muncha