First we make the composition of functions:
f (x) = sin x
g (x) = cos x
f (g (x)) = sin (cos x)
We now evaluate the composite function in pi / 2:
f (g (pi / 2)) = sin (cos (pi / 2))
f (g (pi / 2)) = sin (0)
f (g (pi / 2)) = 0
Answer:
f (g (pi / 2)) = 0
