I think you "lost" the two additional solutions when you multiplied by .
I seem to have partially gotten this right, but am missing some answers, so chances are i stumbled across the (partial) right answer improperly. If someone could tell me what I'm doing wrong, that would be grand
on an interval of 0 - 2pi
using double angle identities and cotanget identity
multiply both sides by tanx
multiply both sides by
so that gives an answer at , but the book specifies additional answers at . Did I make a mistake above? If not, where are those 2 additional answers from?