A function f is an even function, if for all x we have f(x)=f(-x).
All the functions in the problem are constant functions, because no x is involved.
For example, consider the first function: [tex]f(x)=sin(-3 \pi)[/tex],
[tex]sin(-3 \pi )[/tex] is just a constant value.( it is actually equal to 0)
Thus for any x, f(x) = 0 and f(-x) =0
This can be said for all constant functions: all of them are even functions.
Answer: all
