Question 6**For rotations of an equilateral triangle generated by \(r\), where \(r\) is \(120^\circ\), list \(\langle r\rangle\).
Question 10***For a regular pentagon, let \(r\) be rotation by \(72^\circ\). What is the order of \(r\)?
Question 17****+Explain why stopping after seeing several distinct powers is not enough to prove an element generates a finite group.
Question 19*****A student says a group of order \(6\) must be cyclic because repeatedly applying any non-identity element eventually repeats. Diagnose the error.
Question 20*****Show that every subgroup of a cyclic group is generated by powers of the same generator in the finite case, using the smallest positive exponent idea.