It depends on how your triangle is set up. The lengths of the sides form a Pythangorean triple since it has sides of 3,4,5. If the answer is not 3/5, I'm assuming it's 4/5. So I'm guessing this is how your triangle is set up.

Code:

--
- -
- 30 -
- -
4 - - 5
- -
- -
- 90 x -
------------------
3

sin(x) = opp/hyp = 4/5

cos(x) = adj/hyp = 3/5

tan(x) = opp/adj = 4/3

cot(x) is the reciprocal of tan(x). Since tan(x) = 4/3, cot(x) = 3/4

sec(x) is the reciprocal of cos(x). Since cos(x) = 3/5, sec(x) = 5/3

csc(x) is the reciprocal of sin(x). Since sin(x) = 4/5, csc(x) = 5/4

Sorry for the horrible triangle