sine of an angle in degree mode

[BartDB]

So here's my take on it:

If the user enters sin(180) or sin(pi) where pi=symbol of pi
Then the programmer can assume they want the sin of exactly 180 degrees or pi radians.

However, if the numerical value of pi is used then sin(3.14159265359) is entered (showing 12-digit as per most HP calcs)
Then the question is: did the user really want the sin of exactly pi radians or did they want the sin of the approximated value?
As the programmer cannot pre-empt this, the best approach is to provide the answer of the approximated value.

Of course some calculators try to second-guess this and this can lead some interesting answers.

EDIT: note on HP calculators pi is interpreted to its numerical value unless CAS is used if it exists (e.g. Prime CAS mode or 50g symbolic mode).