For each function below enter the letter E if the function is even, the letter O if it's odd, and the letter N if it's neither even nor odd.
$f(x) = \sin x.$
$f(x) = \cos x.$
$f(x) = \tan x.$
$f(x) = (\sin x) (\cos x).$
$f(x) = \sin^2 x$.
Note: Remember that this notation means the square of $\sin x$, i.e., $$\sin^2 x = (\sin x)^2.$$
$f(x) = \cos^2 x$
$f(x) = \sin x + \cos x$