Question

How do i do this problem ?

Answer 1

When it asks for f(-π) or f(0) or f(whatever) it essentially means you need to sub in the values for whatever into the bracket into the function 

so if $f( \theta) =sin(\theta)$

and then you're asked to find f(-π) then it essentially wants you to find sin(-π)

Therefore 

f(-π) = sin(-π) = 0
f(0) = sin (0) = 0
f(π) = sin(π) = 0
f(2π) = sin2π = 0