Mathematica doesn't know Cos[2] or even Sin[12 Degree]!

Question

I tried with some common angles like pi/2, pi/3 or pi/6 but and it works but when you use uncommon angles like 2 rad or 12 degree mathematica doesn't return any value! Please don't tell me mathematica uses a 20 entry table or something like that for cosine and sine!

Answer 1

Since the sin/cos of those angles have no exact representation (like, say Cos[45 Degree] which is 1/sqrt(2)), you'll need to do N[Cos[2]] and N[Sin[12 Degree]] (i.e. N[...]).

In[1]:= Cos[2]
Out[1]:= Cos[2]

In[2]:= N[Cos[2]]
Out[2]:= -0.416147