8. Recall that we can define an inner product on the set PC[a, b] as follows:
$$(f,g) = \int_a^b f(x)g(x)dx$$
, and we can define a norm on the same set as:
$$||f|| = \sqrt{(f,f)}$$
a. Show that the functions $f(x) = x$ and $g(x) = \cos (x)$ are orthogonal in the
set PC[-π, π].
b. Compute the norm $||\cos (x)||$ in the set PC[-π,π].