Question 51
Let $f(x) = \frac{15}{x+1} + \frac{16}{x^2+1} - \frac{17}{x^3+1}$. Find the value of
$f(\tan 15^\circ) + f(\tan 30^\circ) + f(\tan 45^\circ) + f(\tan 60^\circ) + f(\tan 75^\circ)$.
$f(\tan 15^\circ) + f(\tan 30^\circ) + f(\tan 45^\circ) + f(\tan 60^\circ) + f(\tan 75^\circ)$.