well if you have a really really really ugly solution but it works they will probably give you 5 (assuming you dont use a calculator)....
i trig bashed a problem this year and still got a 5 :) :)
if it is not clear though..the grader can take away 1 pt just because they feel like it is poor
then if you use a computer program, they might give you 1 pt (since you show understanding)