That is indeed the right answer, for
n=9, you have nine nodal points if you think of it conceptually,
when as in a regular sin or cos function,
the period is divided by nine causing the graph to split into
nine cycles. -> return to
the questions page
Congratulations 
as in a regular sin or cos function,
the period is divided by nine causing the graph to split into
nine cycles. -> return to
the questions page